Polymeric surface coatings

ABSTRACT

Polymers of one or more radical polymerisable monomers which polymer has pendant groups bearing a centre of permanent positive charge and other pendant groups capable of stably binding the polymer to a surface are useful in the treatment of surfaces to render them biocompatible. The polymers may contain pendant groups which bind the polymer to a surface by physisorption, covalent bonding or ionic interactions. Additionally reactive groups in the polymer may serve as points for attachment of ligands to the polymer when coated on a surface.

This is a divisional of application Ser. No. 08/175,348, filed Mar. 7,1994 now U.S. Pat. No. 5,648,442.

The present invention relates to new polymers, processes for producingthem and processes for coating surfaces with them. The invention alsoprovides improved processes for producing certain monomers and tocertain new monomers used to obtain the polymers. The polymers areuseful for coating surfaces of devices and materials which come intocontact with protein-containing solutions and biological fluids, andrendering the surfaces bio- and haemocompatible. Surfaces may thus berendered suitable for prolonged contact with living tissues and bodyfluids and with protein-containing solutions.

Materials used in the manufacture of separation substrates and devices,blood contacting devices contact and intraocular lenses, and otherdevices which are used in contact with protein-containing or biologicalfluids must be selected on the basis of acceptable physical andmechanical properties and compatibility with the protein-containing orbiological fluid. For any given application of these materials it isusually difficult to optimise all of these considerations simultaneouslyand a compromise must be reached often resulting in less than optimalperformance. For example, major biological problems are oftenencountered with materials which have otherwise optimal mechanical andphysical properties. These problems often manifest themselves asundesirable deposition of biological components and in particularproteinaceous material. This protein adsorption results in blood clotformation in blood-contacting materials, the adsorption of tearcomponents onto contact lenses resulting in deposit formation, formationof deposits on intraocular lenses and in separation media it results inblockage and failure of separation devices. Such effects lead tosignificant loss in operational performance and often complete rejectionand failure of devices.

In the case of medical devices, for example prostheses and components ofblood dialysis equipment, it is common practice to employ biocompatiblepolymers to form at least the surface of the devices to discourageprotein adsorption. However, these materials are not perfect andreaction with the living tissues still remains a problem; for examplesurface-induced thrombosis is still a major difficulty, particularlywhere large quantities of blood are contacted with a foreign surfacesuch as in artificial lungs and kidneys. Formation of a clot in anartificial organ has a number of adverse or even catastrophic effectsincluding occlusion of the blood pathway in the extracorporeal system,or embolism if the clot breaks off the artificial surface and lodges ina host blood vessel. Dialysis membranes, heart valves,circulatory-assist devices, blood substitutes and artificial lungs allshare this problem.

It is known that materials for use as biocompatible coatings shouldideally:

(a) be capable of reproducible manufacture as pure materials;

(b) be capable of being coated onto surfaces without being degraded oradversely changed;

(c) have the requisite mechanical and permeability properties requiredfor the specific function of the device for which they are intended;

(d) be sterilisable without adverse changes in, for example,permeability and mechanical or surface properties;

(e) not be damaged or degraded by the biological environment;

(f) not be carcinogenic.

In applications involving direct contact with blood further restrictionsexist. Materials should not:

(g) induce significant platelet adhesion;

(h) interfere with the normal clotting mechanism; or

(i) cause any significant damage to the cellular elements or solublecomponents of the blood.

There have been many attempts to prepare biocompatible, and specificallyblood compatible (i.e, haemocompatible), surfaces, which do not activatethe blood coagulation process and do not promote thrombus formation.Examples of such attempts include the preparation of negatively chargedsurfaces, such as by use of anionic polymers or suitably orientedelectret polymers, preparation of surfaces coated with the naturalanticoagulant heparin or synthetic heparin analogues, preparation ofsurfaces with inherently low surface free energy such as by use ofsilicone rubber, preparation of albumin-coated surfaces, and preparationof surfaces coated with compounds such as some polymethanes which arethought to adsorb albumin preferentially from blood. All of thesehowever have had limitations.

We have now devised new film-forming polymers which can be used to coatsurfaces. It has been found that these copolymers may be used to providestable coatings on a wide variety of surfaces including, polyethylene,PVC, steel and poly(imide). The invention also provides physiadsorbablepolymers which when used to coat surfaces, do not swell, to anysignificant extent, in aqueous environments; in some situations swellingin aqueous environments can reduce the stability of coatings ofphysiadsorbable polymers on surfaces.

The polymers which contain zwitterionic groups, mimic the zwitterionicstructure of phospholipids such as phosphatidylcholine and sphingomyelinwhich are the major components of the outer membrane of all livingcells. In this way the present invention seeks to provide abiocompatible surface on a coated substrate at which the deposition ofproteins and cells at the substrate is minimised when the coatedsubstrate comes into contact with a protein-containing solution orbiological fluid.

In addition a variety of ligands may be attached to the polymers of thepresent invention when coated onto a substrate. Alternatively ligandsmay be attached to the polymers prior to coating on a substrate, e.g.when the polymer is in solution. The polymers of the present inventionmay therefore provide a means of attachment of such ligands. The termligand includes, but is not limited to, specific binding agents such asimmunoglobulins and associated fragments thereof such as those usefulfor affinity separation and diagnostic applications, photosensitive andchemisensitive moieties such as those useful for detector and sensorapplications and therapeutic agents useful for clinical applications.Other ligands include peptide fragments which may be chemically linkedto a polymer of the invention, such as fragments which induce cellattachment and may therefore be used to allow the polymers of thepresent invention to provide cell seeding.

The present invention provides a polymer of one or more radicalpolymerisable, preferably ethylenically unsaturated, monomers, whichpolymer has pendant groups bearing a centre of permanent positive chargeand other pendant groups capable of stably binding the polymer to asurface. Such coatings bind to surfaces with good adhesion and are notremovable in the environment in which the coated surfaces are used, e.g.in use as a coating on a blood-contacting surface.

Groups bearing a centre of permanent positive charge can be cationic butare most preferably zwitterionic. Such zwitterionic groups mimic thestructure of the head groups of phospholipids in cells. Without wishingto be limited by this theory, it is thought that the presence of suchgroups at a surface renders the surface more biocompatible.

The extent to which a polymer renders a surface biocompatible may beassessed as a combination of factors such as reduction in the extent towhich the surface causes blood platelet activation, protein adsorption,(for instance as judged by absorption of fibrinogen from human plasma)and reaction with C-reactive protein which is caused by the presence onthe surface of isolated zwitterionic, e.g. phosphate ammonium estergroups. Preferably the polymers of the invention when coated onto asubstrate, provide a reduction in platelet activation of at least 70%,more preferably at least 90%, as assessed by the assay describedhereinafter compared to an untreated substrate. It is also preferredthat the polymers of the invention, when coated onto a substrate,provide a reduction in fibrinogen absorption of at least 60% as assessedby the assay described hereinafter and a protein index of less than1.5×10⁻³ compared to an untreated substrate. The protein index isdefined as the ratio of the absorbance due to C-reative protein measuredin the assay described hereinafter to the reduction in fibrinogenadsorption.

The nature of the groups capable of binding the polymer to a surfacewill be selected depending upon the nature of the surface which it isintended to coat with the polymer. Where the surface is hydrophobic,groups capable of being physisorbed at the surface may be used to bindthe polymer to the surface. Where the surface is hydrophilic and bearsfunctional groups then groups which are capable of reacting with surfacefunctional groups to form covalent bonds may be used to bind the polymerto the surface. Where the surface is charged then groups bearing ioniccharge may be used to bind the polymer to the surface by ionicinteractions.

Polymers of the invention may therefore bind to a surface byphysisorption, covalent or ionic bonding depending upon the precisenature of the surface. In certain cases it may be possible to use two ofthese binding mechanisms in combination.

The groups capable of stably binding the polymer to a surface may bepresent in the same monomer as the groups bearing a centre of permanentpositive charge, or they may be in separate monomer species which arecopolymerised to provide the polymer of the invention.

It will be understood that throughout, where a group is referred to ascapable of binding a polymer to a surface this is intended to meanstably binding.

Where a hydrophobic surface is to be coated, alkyl groups of 6 or morecarbon atoms, or fluoroalkyl groups, optionally having one or moreetheric oxygen atoms interrupting the carbon chain, and optionallycontaining one or more carbon-carbon double or triple bonds, or siloxanegroups, preferably containing from 1 to 50, more preferably 5 to 30,silicon atoms, may be used as the pendant groups capable of binding thepolymer to a surface. Such groups are capable of forming strongsecondary valence interactions with a surface, and being physisorbed ata hydrophobic surface, i.e. adsorbed without formation of a covalentinteraction.

In one embodiment the present invention therefore provides a polymerobtainable by

(i) copolymerising a radical polymerisable, preferably an ethylenicallyunsaturated, comonomer containing a group bearing a centre of permanentpositive charge, which is preferably zwitterionic, and a radicalpolymerisable, preferably an ethylenically unsaturated, comonomercontaining a radical polymerisable moiety and an alkyl group of 6 ormore carbon atoms, which alkyl group optionally contains one or moreetheric oxygen atoms and optionally one or more carbon-carbon double ortriple bonds, or a fluoroalkyl group which optionally contains one ormore etheric oxygen atoms and optionally one or more carbon-carbondouble or triple bonds, or a siloxane group; or

(ii) polymerising a radical polymerisable, preferably ethylenicallyunsaturated, monomer containing a group bearing a centre of permanentpositive charge which is preferably zwitterionic, and an alkyl group of6 or more carbon atoms, which alkyl group optionally contains one ormore etheric oxygen atoms, or a fluoroalkyl group which optionallycontains one or more etheric oxygen atoms, or a siloxane group.

Such a polymer may be a copolymer comprising residues of a radicalpolymerisable, preferably ethylenically unsaturated, comonomercontaining a group bearing a centre of permanent positive charge and ofa radical polymerisable, preferably ethylenically unsaturated comonomercontaining, in addition to the radical polymerisable moiety, an alkylgroup of 6 or more carbon atoms which group optionally contains one ormore etheric oxygen atoms and optionally one or more carbon-carbondouble or triple bonds or a fluoroalkyl group which optionally containsone or more etheric oxygen atoms and optionally one or morecarbon-carbon double or triple bonds, or a siloxane group.

Alternatively such a polymer may comprise or consist of residues of aradical polymerisable, preferably ethylenically unsaturated, monomercontaining a group bearing a centre of permanent positive charge and analkyl group of 6 or more carbon atoms which group optionally containsone or more etheric oxygen atoms or a fluoroalkyl group which optionallycontains one or more etheric oxygen atoms, or a siloxane group.

In this embodiment, preferably the polymer is a copolymer comprisingresidues of a comonomer containing a physisorbable group and a comonomercontaining a group bearing a centre of permanent positive charge.

It is also preferred that the physisorbable group is an alkyl orfluoroalkyl group optionally containing one or more carbon-carbon doubleor triple bonds. Such a group may contain one or more etheric oxygenatoms, but in an especially preferred embodiment does not contain anyetheric oxygen atoms.

In one embodiment, where the physisorbable group is an alkyl orfluoroalkyl group, optionally containing one or more etheric oxygenatoms, this group does not contain any carbon-carbon double or triplebonds.

Where a hydrophilic surface having functional groups is to be coated,groups capable of covalently binding the polymer to the surface may beincorporated into the polymer as pendant groups.

Thus according to an alternative embodiment, the invention provides apolymer obtainable by:

(i) copolymerising a radical polymerisable, preferably ethylenicallyunsaturated, comonomer containing a group bearing a centre of permanentpositive charge, which is preferably zwitterionic, and a radicalpolymerisable, preferably ethylenically unsaturated, comonomer bearing areactive group capable of covalently binding the polymer to a surface;or

(ii) polymerising a radical polymerisable, preferably ethylenicallyunsaturated, monomer containing a group bearing a centre of permanentpositive charge, which is preferably zwitterionic, and a reactive groupcapable of covalently binding the polymer to a surface.

Such a polymer may be a copolymer comprising residues of a radicalpolymerisable, preferably ethylenically unsaturated, comonomercontaining a group bearing a centre of permanent positive charge and aradical polymerisable, preferably ethylenically unsaturated, comonomerbearing a reactive group and is capable of covalently binding to asurface.

Alternatively, such a polymer may comprise or consist of residues of aradical polymerisable, preferably ethylenically unsaturated, monomercontaining a group bearing a centre of permanent positive charge and areactive group capable of covalently binding to a surface.

In this embodiment, preferably the polymer is a copolymer comprisingresidues of a comonomer containing a group bearing a centre of permanentpositive charge and a comonomer containing a reactive group capable ofcovalently binding to the surface.

Where a surface bearing an ionic charge is to be coated, ionic groups,capable of binding the polymer to the surface by ionic interactions, maybe incorporated into the polymer of the invention as pendant groups.

According to a third embodiment, the invention therefore provides apolymer obtainable by:

(i) copolymerising a radical polymerisable, preferably ethylenicallyunsaturated, comonomer containing a group bearing a centre of permanentpositive charge which is preferably zwitterionic, and a radicalpolymerisable, preferably ethylenically unsaturated, comonomer bearingan ionic group capable of binding to a surface by ionic interaction; or

(ii) polymerising a radical polymerisable, preferably ethylenicallyunsaturated, monomer containing a group bearing a centre of permanentpositive charge, which is preferably zwitterionic, and an ionic groupcapable of binding to a surface by ionic interaction.

Such a polymer may be a copolymer comprising residues of a radicalpolymerisable, preferably ethylenically unsaturated, comonomercontaining a group bearing a centre of permanent positive charge, andresidues of a comonomer containing an ionic group capable of binding toa surface by ionic interaction.

Alternatively such a polymer may comprise or consist of residues of aradical polymerisable, preferably ethylenically unsaturated, monomercontaining a group bearing a centre of permanent positive charge and anionic group capable of binding to a surface by ionic interaction.

In this embodiment, preferably the polymer is a copolymer comprisingresidues of a comonomer containing a group bearing a centre of permanentpositive charge and residues of a comonomer containing an ionic groupcapable of binding to a surface by ionic interaction.

Optionally, in any of the above embodiments, the polymers also compriseresidues of one or more diluent and/or crosslinkable monomers.

The invention also provides a process for producing such a polymer whichcomprises polymerising such monomers and a process for coating a surfacewith such a polymer, for instance a process comprising the steps of (a)polymerising such monomers to form the polymer and (b) coating thesurface with the polymer so formed. Optionally, the process furthercomprises attaching a ligand to the polymer either in solution beforecoating the surface, or, more preferably when coated on the surface.

In a specific embodiment the invention further provides such polymerscontaining residues of a crosslinkable monomer, which are uncrosslinked,when either coated on a surface or not coated on a surface and suchpolymers which are crosslinked when coated on a surface. The inventionfurther provides a process of crosslinking such polymers when coated ona surface.

As yet a further feature, the present invention provides certain newmonomers useful in producing the polymers of the invention.

Monomers and comonomers which may be used in the polymers of theinvention will now be described in more detail.

It is to be understood that throughout the specification (alk)acrylate,(alk)acrylic and (alk)acrylamide mean acrylate or alkacrylate, acrylicor alkacrylic and acrylamide or alkacrylamide respectively. Preferablyunless otherwise stated alkacrylate, alkacrylic and alkacrylamide groupscontain from 1 to 4 carbon atoms in the alkyl group thereof and are mostpreferably methacrylate, methacrylic or methacrylamide groups. Similarly(meth)acrylate, (meth)acrylic and (meth)acrylamide shall be understoodto mean acrylate or methacrylate, acrylic or methacrylic and acrylamideor methacrylamide respectively.

Monomers Bearing A Centre of Permanent Positive Charge.

The monomer (or comonomer) bearing the centre of permanent positivecharge can either be cationic or, more preferably zwitterionic. In thelatter case the monomer includes within its structure not only a centreof permanent positive charge but also a centre of negative charge.Typically the centre of permanent positive charge is provided by aquaternary nitrogen atom.

Preferred comonomers which bear a centre of positive charge are ofgeneral formula (I)

    Y--B--X                                                    (I)

wherein B is a straight or branched alkylene, oxaalkylene oroligo-oxaalkylene chain optionally containing one or more fluorine atomsup to and including perfluorinated chains or, if X contains acarbon-carbon chain between B and the centre of permanent positivecharge or if Y contains a terminal carbon atom bonded to B, a valencebond;

X is a group bearing a centre of permanent positive charge, preferably azwitterionic group and

Y is an ethylenically unsaturated polymerisable group selected from##STR1## wherein: R is hydrogen or a C₁ -C₄ alkyl group;

A is --O-- or --NR¹ -- where R¹ is hydrogen or a C₁ -C₄ alkyl group orR¹ is --B--X where B and X are as defined above; and

K is a group --(CH₂)_(p) OC(O)--, --(CH₂)_(p) C(O)O--, --(CH₂)_(p)OC(O)O--, --(CH₂)_(p) NR² --, --(CH₂)_(p) NR² C(O)--, --(CH₂)_(p)C(O)NR² --, --(CH₂)_(p) NR² C(O)O--, --(CH₂)_(p) OC(O)NR² --,--(CH₂)_(p) NR² C(O)NR² --, (in which the groups R² are the same ordifferent) --(CH₂)_(p) O--, --(CH₂)_(p) SO₃ --, or, optionally incombination with B, a valence bond and p is from 1 to 12 and R² ishydrogen or a C₁ -C₄ alkyl group.

The proviso on whether B may be a valence bond ensures that the centreof permanent positive charge in X is not directly bonded to aheteroatom, such as an oxygen or nitrogen atom in Y.

Preferred monomers containing a group bearing a centre of permanentpositive charge are therefore of general formula (II) or (III). ##STR2##where R, A, B, K and X are as defined with reference to formula (I).

Preferably in the compounds of formula (II) R is hydrogen, methyl, orethyl, more preferably methyl, so that (II) is an acrylic acid,methacrylic acid or ethacrylic acid derivative.

In the compounds of formula (III) K may be a valence bond and B a group,K may be a group and B a valence bond, both K and B may be groups, or Kand B may together be a valence bond. Preferably B is a group where K isa valence bond.

Where K is a group then preferably p is from 1 to 6, more preferably 1,2or 3 and most preferably p is 1. When K.is a group --(CH₂)_(p) NR² --,--(CH₂)_(p) NR² C(O)--, --(CH₂)_(p) C(O)NR², --(CH₂)_(p) NR² C(O)O--,--(CH₂)_(p) OC(O)NR² -- or --(CH₂)_(p) NR² C(O)NR2-- then R² ispreferably hydrogen, methyl or ethyl, more preferably hydrogen.

In the compounds of formula (III) preferably the vinyl group is para tothe group --K--B--X.

Preferably B is:

an alkylene group of formula --(CR³ ₂)_(a) --, wherein the groups --(CR³₂)-- are the same or different, and in each group --(CR³ ₂)-- the groupsR³ are the same or different and each group R³ is hydrogen, fluorine orC₁₋₄ alkyl or fluroalkyl, preferably hydrogen, and a is from 1 to 12,preferably 1 to 6;

an oxaalkylene group such as alkoxyalkyl having 1 to 6 carbon atoms ineach alkyl moiety, more preferably --CH₂ O(CH₂)₄ --; or

an oligo-oxaalkylene group of formula -- (CR⁴ ₂)_(b) O!_(c) (CR⁴ ₂)_(b)-- where the groups --(CR⁴ ₂)-- are the same or different and in eachgroup --(CR⁴ ₂)-- the groups R⁴ are the same or different and each groupR⁴ is hydrogen, fluorine or C₁₋₄ alkyl or fluoroalkyl, preferablyhydrogen, and b is from 1 to 6, preferably 2 or 3 and c is from 2 to 11,preferably 2 to 5; or

if X contains a carbon-carbon chain between B and the centre ofpermanent positive charge or if Y contains a terminal carbon atom, avalence bond.

Preferred groups B include alkylene, oxaalkylene and oligo-oxaalkylenegroups of up to 12 carbon atoms optionally containing one or morefluorine atoms. Where the polymer is not intended for coating ahydrophobic surface, and therefore is not intended to be bound byphysiosorption to a surface, then preferably B is an alkylene,oxaalkylene or oligo-oxaalkylene group which does not contain anyfluorine atoms.

In compounds of formula (III) it is preferred that K and B contain up to12 carbon atoms in total.

Preferred groups X containing a centre of permanent positive charge, arethe groups of formula (IVA), (IVB), (IVC), (IVD), (IVE) and (IVF) asdefined below: monomers containing such groups may be used incombination with further monomers containing groups capable of bindingto a surface, to provide a copolymer of the invention. Of these groupsof formula (IVB)-(IVF) and especially (IVC) are particularly preferred.

In addition, groups of formula (VA), (VB) and (VC) are preferred asmonomers containing both a centre of permanent positive charge and analkyl, fluoroalkyl or siloxane group capable of binding to a surface byphysisorption.

The groups of formula (IVA) are:

    --N.sup.⊕ (R.sup.5), Z.sup.⊖                   (IVA)

where the groups R⁵ are the same or different and each is hydrogen orC₁₋₄ alkyl and Z is a counter ion.

Preferably the groups R⁵ are all the same. It is also preferable that atleast one of the groups R⁵ is methyl, and more preferable that all thegroups R⁵ are methyl.

The counterion Z present in the compounds of formula (II) or (III)containing a group of formula (IVA) is such that the compounds areneutral salts. The counterion may be exchanged with ions inphysiological fluids and thus the specific nature of the counterion isnot critical in the present invention. However, physiologicallyacceptable counterions are preferred. Suitable physiologicallyacceptable counterions include halide anions, such as chloride orbromide ions, other inorganic anions such as sulphate, phosphate andphosphite and organic anions such as aliphatic mono-, di- ortri-carboxylate anions containing from 2 to 25 carbons atoms andoptionally bearing one or more hydroxyl groups e.g. acetate, citrate andlactate.

When X is a group of formula (IVA), preferably B is a group of formula--(CR³ ₂)-- or --(CR³ ₂)₂ --, eg. --(CH₂)-- or --(CH₂ CH₂)--.

The groups of formula (IVB) are: ##STR3## where the groups R⁶ are thesame or different and each is hydrogen or C₁₋₄ alkyl and d is from 2 to4.

Preferably the groups R⁶ are the same. It is also preferable that atleast one of the groups R⁶ is methyl, and more preferable that thegroups R⁶ are both methyl.

Preferably d is 2 or 3, more preferably 3.

When X is a group of formula (IVB) preferably B is a group of formula--(CR³ ₂)-- or --(CR³ ₂)₂ --, eg. --(CH₂)-- or --(CH₂ CH₂)--.

The groups of formula (IVC) are: ##STR4## where the groups R⁷ are thesame or different and each is hydrogen or C₁₋₄ alkyl, and e is from 1 to4.

Preferably the groups R⁷ are the same. It is also preferable that atleast one of the groups R⁷ is methyl, and more preferable that thegroups R⁷ are all methyl.

Preferably e is 2 or 3, more preferably 2.

When X is a group of formula (IVC) preferably B is a group of formula--(CR³ ₂)-- or --(CR³ ₂)₂ --, eg. --(CH₂)--or --(CH₂ CH₂)--.

The groups of formula (IVD) are: ##STR5## wherein the groups R⁸ are thesame or different and each is hydrogen or C₁₋₄ alkyl, R^(8a) is hydrogenor, more preferably, a group --C(O)B¹ IR^(8b) where R^(8b) is hydrogenor methyl, preferably methyl, B¹ is a valence bond or straight orbranched alkylene, oxaalkylene or oligo-oxaalkalyene group, and f isfrom 1 to 4; and

if B is other than a valence bond Z is 1 and if B is a valence bond Z isO, if X is directly bonded to an oxygen or nitrogen atom and otherwise Zis 1.

Preferably the groups R⁸ are the same. It is also preferable that atleast one of the groups R⁸ is methyl, and more preferable that thegroups R⁸ are all methyl.

Preferably f is 1 or 2, more preferably 2.

Preferably B¹ is:

a valence bond;

an alkylene group of formula --(CR^(3a) ₂)_(aa) --, wherein the groups--(CR^(3a) ₂)-- are the same or different, and in each group --(CR^(3a)₂)-- the groups R^(3a) are the same or different and each group R^(3a)is hydrogen or C₁₋₄ alkyl, preferably hydrogen, and aa is from 1 to 12,preferably 1 to 6;

an oxaalkylene group such as alkoxyalkyl having 1 to 6 carbon atoms ineach alkyl moiety, more preferably --CH₂ O(CH₂)₄ --; or

an oligo-oxaalkylene group of formula -- (CR^(4a) ₂)_(ba) O!_(ca) --where the groups --(CR_(4a) ₂)-- are the same or different and in eachgroup --(CR^(4a) ₂)-- the groups R^(4a) are the same or different andeach group R^(4a) is hydrogen or C₁₋₄ alkyl, preferably hydrogen, and bais from 1 to 6, preferably 2 or 3, and ca is from 1 to 12, preferably 1to 6.

Preferred groups B¹ include a valence bond and alkylene, oxaalkylene andoligo-oxaalkylene groups of up to 12 carbon atoms.

Preferably B and B¹ are the same.

When X is a group of formula (IVD) preferably B is a group of formula --(CR⁴ ₂ CR⁴ ₂)_(c) O_(b) !CR⁴ ₂ CR⁴ ₂ --, eg. --(CH₂ CH₂ O)_(c) (CH₂CH₂)--.

The groups of formula (IVE) are: ##STR6## wherein the groups R⁹ are thesame or different and each is hydrogen or C₁ -CH₄ alkyl, R^(9a) is ahydrogen or, more preferably, a group --C(O)B² R^(9b), R^(9b) ishydrogen or methyl, preferably methyl, B² is a valence bond or astraight or branched alkylene, oxaalkylene or oligo-oxaalkylene group,and g is from 1 to 4; and

if B is other than a valence bond Z is 1 and if B is a valence bond Z isO if X is directly bonded to an oxygen or nitrogen atom and otherwise Zis 1.

Preferably the groups R⁹ are the same. It is also preferable that atleast one of the groups R⁹ is methyl, and more preferable that thegroups R⁹ are all methyl.

Preferably g is 1 or 2, more preferably 2.

Preferably B² is:

a valence bond;

an alkylene group of formula --(CR^(3b) ₂)_(ab) --, wherein the groups--(CR^(3b) ₂)-- are the same or different, and in each group --(CR^(3b)₂)-- the groups R^(3b) are the same of different and each group R^(3b)is hydrogen or C₁₋₄ alkyl, preferably hydrogen, and ab is from 1 to 12,preferably 1 to 6;

an oxaalkylene group such as alkoxyalkyl having 1 to 6, carbon atoms ineach alkyl moiety, more preferably --CH₂ O(CH₂)₄ --; or

an oligo-oxaalkylene group of formula -- (CR^(4b) ₂)_(bb) O!_(cb) --where the groups --(CR^(4b) ₂)-- are the same or different and in eachgroup --(CR^(4b) ₂) the groups R^(4b) are the same or different and eachgroup R^(4b) is hydrogen or C₁₋₄ alkyl, preferably hydrogen, and bb isfrom 1 to 6, preferably 2 or 3, and cb is from 1 to 12, preferably 1 to6.

Preferred groups B² include a valence bond and alkylene, oxalkylene andoligo-oxalkylene groups of up to 12 carbon atoms.

Preferably B and B² are the same.

When X is a group of formula (IVE) preferably B is a group of formula --(CR⁴ ₂ CR⁴ ₂)_(b) O!_(c) CR⁴ ₂ CR⁴ ₂ --, eg. --(CH₂ CH₂ O)_(c) CH₂ CH₂--.

The groups of formula (IVF) are: ##STR7## wherein the groups R¹⁰ are thesame or different and each is hydrogen or C₁₋₄ alkyl, R^(10a) ishydrogen or, more preferably, a group --C(O)B³ R^(10b) where R^(10b) ishydrogen or methyl, preferably methyl, B³ is a valence bond or astraight or branched alkylene, oxaalkylene or oligo-oxaalkylene group,and h is from 1 to 4; and

if B is other than a valence bond Z is 1 and if B is a valence bond Z is0 if X is directly bonded to the oxygen or nitrogen and otherwise Z is1.

Preferably the groups R¹⁰ are the same. It is also preferable that atleast one of the groups R¹⁰ is methyl, and more preferable that thegroups R¹⁰ are all methyl.

Preferably h is 1 or 2, more preferably 2.

Preferably B³ is:

a valence bond;

an alkylene group of formula --(CR^(3c) ₂)_(ac) --, wherein the groups--(CR^(3c) ₂)-- are the same or different, and in each group --(CR^(3c)₂)-- the groups R^(3c) are the same or different and each group R^(3c)is hydrogen or C₁₋₄ alkyl, preferably hydrogen, and ac is from 1 to 12,preferably 1 to 6;

an oxaalkylene group such as alkoxyalkyl having 1 to 6 carbon atoms ineach alkyl moiety, more preferably --CH₂ O(CH₂)₄ --; or

an oligo-oxaalkylene group of formula -- (CR^(4c) ₂)_(bc) O!_(cc) --where the groups --(CR^(4c) ₂)-- are the same or different and in eachgroup --(CR^(4c) ₂)-- the groups R^(4c) are the same or different andeach group R^(4c) is hydrogen or C₁₋₄ alkyl, preferably hydrogen, and bcis from 1 to 6, preferably 2 or 3, and cc is from 1 to 12, preferably 1to 6.

Preferred groups B³ include a valence bond and alkylene, oxaalkylene andoligo-oxaalkylene groups of up to 12 carbon atoms.

Preferably B and B³ are the same.

When X is a group of formula (IVF) preferably B is a group of formula --(CR⁴ ₂ CR⁴ ₂)_(b) O!_(c) CR.sup.₂ CR⁴ ₂ --, eg. --(CH₂ CH₂ O)_(c) CH₂CH₂ --.

Further groups bearing a centre of permanent positive charge are offormula (VA), (VB) and (VC). These groups also contain an alkyl orfluoroalkyl group capable of binding to a surface by physisorption.Monomers containing such a group are therefore particularly suitable foruse in the polymers of the invention, optionally without separatecomomoners containing a group capable of binding to a hydrophobicsurface by physisorption.

The groups of formula (VA) are: ##STR8## wherein the groups R¹¹ are thesame or different and each is hydrogen or C₁₋₄ alkyl, R^(11a) is either

(a) a group -- C(O)!_(vw) (CR^(11b) ₂)_(ww) (SiR^(11c) ₂) (OSiR^(11c)₂)_(vv) R^(11c) in which each group R^(11b) is the same or different andis hydrogen or alkyl of 1 to 4 carbon atoms, each group R^(11c) is thesame or different and is alkyl of 1 to 4 carbon atoms or aralkyl, forexample benzyl or phenethyl, vw is 0 or 1, ww is from 0 to 6 with theproviso that vw and ww are not both 0, and vv is from 0 to 49;

(b) a group of formula --C(O)B⁴ --R^(11d), in which R^(11d) is hydrogenor methyl, B⁴ is a valence bond or straight or branched alkylene,oxaalkylene or oligo-oxaalkalyene group optionally containing one ormore fluorine atoms, and containing from 6 to 24, preferably 6 to 18carbon atoms; i is from 1 to 4; and

if B is other than a valence bond Z is 1 and if B is a valence bond Z is0 if X is directly bonded to an oxygen or nitrogen atom and otherwise Zis 1.

Preferably the groups R¹¹ are the same. It is also preferable that atleast one of the groups R¹¹ is methyl, and more preferable that thegroups R¹¹ are all methyl.

Preferably i is 1 or 2, more preferably 2.

Where R^(11a) is a siloxane group as defined in (a) above, each group(CR^(11b) ₂) may be the same or different, preferably the same, andpreferably each group R^(11b) is hydrogen. Preferably ww is from 2 to 4,and is most preferably 3 when vw is 0 or 2 when vw is 1. Each group(SiR^(11c) ₂) may be the same or different, preferably the same, andpreferably each group R^(11c) is methyl. Preferably vv is from 4 to 29.

Preferably the group R^(11a) is a group --C(O)B⁴ R^(11d) as definedabove. In such a case, preferably B⁴ is:

a valence bond;

an alkylene group of formula --(CR^(3d) ₂)_(ad) --, wherein the groups--(CR^(3d) ₂)-- are the same or different, and in each group --(CR^(3d)₂)-- the groups R^(3d) are the same or different and each group R^(2d)is hydrogen, fluorine or C₁₋₄ alkyl or fluoroalkyl, preferably hydrogenor fluorine, and ad is from 1 to 24, preferably 6 to 18;

an oxaalkylene group such as alkoxyalkyl having 1 to 6 carbon atoms andoptionally one or more fluorine atoms in each alkyl moiety, or

an oligo-oxalkylene group of formula -- (CR^(4d) ₂)_(bd) O!_(cd) --where the groups --(CR^(4d) ₂)-- are the same or different and in eachgroup --(CR^(4d) ₂)-- the groups R^(4d) are the same or different andeach group R^(4d) is hydrogen, fluorine or C₁₋₄ alkyl or fluoroalkyl,preferably hydrogen or fluorine, and bd is from 2 to 6, preferably 3 or4, and cd is from 1 to 12, preferably 1 to 6.

When B⁴ is a group -- (CR^(4d) ₂)_(bd) O!_(cd) -- wherein all the groupsR^(4d) are hydrogen and in all the groups -- (CR^(4d) ₂)_(bd) O!-- bd is2, the residues of the monomer of formula (VA) are not able to formstrong secondary valence interactions with hydrophobic surfaces. Whilstresidues of such monomers may be included in the polymers of theinvention, it is usually also necessary to include residues of monomerswhich are capable of forming strong secondary valence interactions ifsuch interactions are to bind a polymer to a surface.

Monomers which have groups containing oligo(higher alkylene) oxidemoieties can be used to provide strong secondary valence interactions,so can monomers which contain oligo alkylene oxide moieties in which atleast 50, preferably 70, more preferably 90 mol % of individual alkyleneoxide units contain 3 or more carbon atoms. Thus, for instance a mixedoligo(ethylene oxide/propylene oxide) side chain could be used providedthat there are more propylene oxide units than ethylene oxide units.

When B⁴ is a group -- (CR⁴ ₂)_(bd) O!-- then preferably bd is 2 in only50, preferably 70, more preferably 90 mole % or less of the residues --(CR^(4d) ₂)_(bd) O--.

When the group --B⁴ --R^(11a) is a group capable of forming strongsecondary valence interactions with a surface, then monomers containinga group (VA) may be particularly suitable for use as monomers containinga group bearing a centre of permanent positive charge and an alkyl orfluoroalkyl group optionally containing one or more etheric oxygenatoms. Preferably, in such a case --B⁴ --R^(11a) is an alkyl groupoptionally containing one or more etheric oxygen atoms and preferably 6or more carbon atoms or a fluoroalkyl group optionally containing one ormore etheric oxygen atoms and preferably 6 or more carbon atoms.

In one embodiment B and B⁴ may be the same.

The groups of formula (VB) are: ##STR9## wherein the groups R¹² are thesame or different and each is hydrogen or C₁ -C₄ alkyl, R^(12a) iseither

(a) a group -- C(O)!_(tu) (CR^(12b) ₂)_(uu) (SiR^(12c) ₂) (OSiR^(12c)₂)_(tt) R^(12c) in which each group R^(12b) is the same or different andis hydrogen or alkyl of 1 to 4 carbon atoms, each group R^(12c) is thesame or different and is alkyl of 1 to 4 carbon atoms or aralkyl, forexample benzyl or phenethyl, tu is 0 or 1, uu is from 0 to 6, with theproviso that tu and uu are not both 0, and tt is from 0 to 49; or

(b) a group of formula --C(O)B⁵ --R^(12d) in which R^(12d) is hydrogenor methyl, B⁵ is a valence bond or a straight or branched alkylene,oxaalkylene or oligo-oxaalkylene group optionally containing one or morefluorine atoms and from 6 to 24 carbon atoms, more preferably 6 to 18carbons atoms,

j is from 1 to 4; and

if B is other than a valence bond, Z is 1 and if B is a valence bond Zis 0 if X is directly bonded to an oxygen or nitrogen atom and otherwiseZ is 1.

Preferably the groups R¹² are the same. It is also preferable that atleast one of the groups R¹² is methyl, and more preferable that thegroups R¹² are all methyl.

Preferably j is 1 or 2, more preferably 2.

Where R^(12a) is a siloxane group as defined in (a) above, each group(CR^(12b) ₂) may be the same or different, preferably the same, andpreferably each group R^(12b) is hydrogen. Preferably uu is from 2 to 4,and is most preferably 3 when tu is 0 or 2 when tu is 1. Each group(SiR^(12c) ₂) may be the same or different, preferably the same, andpreferably each group R^(12c) is methyl. Preferably tt is from 4 to 29.

Preferably the group R^(12c) is a group --C(O)B⁴ R^(12d) as definedabove. In such a case, preferably B⁵ is:

a valence bond;

an alkylene group of formula --(CR^(3c) ₂)_(ac) --, wherein the groups--(CR^(3c) ₂)-- are the same or different, and in each group --(CR^(3c)₂)-- the groups R^(3c) are the same of different and each group R^(3c)is hydrogen, fluorine or C₁₋₄ alkyl, or fluoroalkyl, preferably hydrogenor fluorine, and ae is from 1 to 24, preferably 6 to 18;

an oxaalkylene group such as alkoxyalkyl having 1 to 6 carbon atoms andoptionally one or more fluorine atoms in each alkyl moiety; or

an oligo-oxaalkylene group of formula -- (CR^(4c) ₂)_(bc) -- where thegroups --(CR^(4c) ₂)-- are the same or different and in each group--(CR^(4c) ₂)-- the groups R^(4c) are the same or different and eachgroup R^(4c) is hydrogen, fluorine or C₁₋₄ alkyl or fluoroalkyl,preferably hydrogen or fluorine, and be is from 2 to 6, preferably 3 or4, and ce is from 1 to 12, preferably 1 to 6.

When B⁵ is a group -- (CR^(4c) ₂)_(bc) O!-- wherein all the groupsR^(4c) are hydrogen and in all the groups CR^(4c) ₂)_(bc) O! be is 2,the residues of the monomer of formula (VB) are not able to form strongsecondary valence interactions with hydrophobic surfaces. Whilstresidues of such monomers may be included in the polymers of theinvention, it is also necessary to include residues of monomers whichare capable of forming such strong secondary valence interactions ifsuch interactions are to bind a polymer to a surface. Monomers whichhave groups containing oligo(higher alkylene) oxide moieties can be usedto provide the necessary strong secondary valence interactions, so canmonomers which contain oligo alkylene oxide moieties in which at least50, preferably 70, more preferably 90 mol % of individual alkylene oxideunits contain 3 or more carbon atoms. Thus, for instance a mixedoligo(ethylene oxide/propylene oxide) side chain could be used providedthat there are more propylene oxide units than ethylene oxide units.

When B⁵ is a group -- (CR^(4c) ₂)_(bc) O!_(cc) -- then preferably be is2 in only 50, preferably 70, more preferably 90 mole % or less of theresidues --C(CR^(4b) ₂)_(bc) O!--.

When the group --B⁵ --R^(12a) is a group capable of forming strongsecondary valence interactions with a surface, then monomers containinga group (VB) may be particularly suitable for use as monomers containinga group bearing a centre of permanent positive charge and an alkyl orfluoroalkyl group optionally containing one or more etheric oxygenatoms. Preferably, in such a case --B⁵ --R¹² a is an alkyl groupoptionally containing one or more etheric oxygen atoms and preferably 6or ore carbon atoms or a fluoroalkyl group optionally containing one ormore etheric oxygen atoms and preferably 6 or more carbon atoms.

In one embodiment B and B⁵ may be the same.

The groups of formula (VC) are: ##STR10## wherein the groups R¹³ are thesame or different and each is hydrogen or C₁₋₄ alkyl, R^(13a) is either

(a) a group -- C(O) !_(rs) (CR^(13b) ₂)_(ss) (SiR^(13c) ₂) (OSiR^(13c)₂)_(rr) R^(13c) in which each group R^(13b) is the same or different andis hydrogen or alkyl of 1 to 4 carbon atoms, each group R^(13c) is thesame or different and is alkyl of 1 to 4 carbon atoms or aralkyl, forexample benzyl or phenethyl, rs is 0 or 1, ss is from 0 to 6, with theproviso that rs and ss are not both 0, and rr is from 0 to 49; or

(b) a group of formula --C(O)B⁶ --R^(13d), in which R^(13a) is hydrogenor methyl, B⁶ is a valence bond or a straight or branched alkylene,oxaalkylene or oligo-oxaalkylene group optionally containing one or morefluorine atoms and from 6 to 24, more preferably 6 to 18 carbon atomsand k is from 1 to 4; and

if B is other than a valence bond, Z is 1 and if B is a valence bond Zis 0 if X is directly bonded to an oxygen or nitrogen atom and otherwiseZ is 1.

Preferably the groups R¹³ are the same. It is also preferable that atleast one of the groups R¹³ is methyl, and more preferable that thegroups R¹³ are all methyl.

Preferably k is 1 or 2, more preferably 2.

Where R^(13a) is a siloxane group as defined in (a) above, each group(CR^(13b) ₂) may be the same or different, preferably the same andpreferably each group R^(13b) is hydrogen. Preferably ss is from 2 to 4,and is most preferably 3 when rs is 0 or 2 when rs is 1. Each group(SiR^(13c) ₂) may be the same, or different, preferably the same, andpreferably each group R^(13c) is methyl. Preferably rr is from 4 to 29.

Preferably the group R^(13a) is a group --C(O)B ⁶ R^(13d) as definedabove. In such a case, preferably B⁶ is:

a valence bond;

an alkylene group of formula --(CR^(3f) ₂)_(af) --, wherein the groups--(CR^(3f) ₂)-- are the same or different, and in each group -- (CR^(3f)₂)-- the groups R^(3f) are the same or different and each group R^(3f)is hydrogen, fluorine or C₁₋₄ alkyl or fluoroalkyl, preferably hydrogenor fluorine, and is from 1 to 24, preferably 6 to 18;

an oxaalkylene group such as alkoxyalkyl having 1 to 6 carbon atoms andoptionally one or more fluorine atoms in each alkyl moiety; or

an oligo-oxaalkylene group of formula -- (CR^(4f) ₂)_(bf) O!_(cf) --where the groups --(CRf₂)-- are the same or different and in each group--(CR^(4f) ₂)-- the groups R^(4f) are the same or different and eachgroup R^(4f) is hydrogen, fluorine or C₁₋₄ alkyl or fluoroalkyl,preferably hydrogen or fluorine, and bf is from 2 to 6, preferably 3 or4, and cf is from 1 to 12, preferably 1 to 6.

When B⁶ is a group -- (CR^(4f) ₂)_(bf) O!_(cf) -- wherein all the groupsR^(4f) are hydrogen and in all the groups (CR^(4c).sub. 2)_(bf) O! bf is2, the residues of the monomer of formula (VC) are not able to formstrong secondary valence interactions with hydrophobic surfaces. Whilstresidues of such monomers may be included in the polymers of theinvention, it is also necessary to include residues of monomers whichare capable of forming such strong secondary valence interactions ifsuch interactions are to bind a polymer to a surface. Monomers whichhave groups containing oligo(higher alkylene) oxide moieties can be usedto provide the necessary strong secondary valence interactions, so canmonomers which contain oligo alkylene oxide moieties in which at least50, preferably 70, more preferably 90 mol % of individual alkylene oxideunits contain 3 or more carbon atoms. Thus, for instance a mixedoligo(ethylene oxide/propylene oxide) side chain could be used providedthat these are more propylene oxide units then ethylene oxide units.

When B⁶ is a group -- (CR^(4f) ₂)_(bf) O!_(cf) -- then preferably bf is2 in only 50, preferably 70, more preferably 90 mol % or less of theresidues -- (CR^(4f) ₂)_(bf) O!--.

When the group --B⁶ --R^(13a) is a group capable of forming strongsecondary valence interactions with a surface, then monomers containinga group (VC) may be particularly suitable for use as monomers containinga group bearing a centre of permanent positive charge and an alkyl orfluoroalkyl group optionally containing one or more etheric oxygenatoms. Preferably, in such a case --B⁶ --RI^(13a) is an alkyl groupoptionally containing one or more etheric oxygen atoms and preferably 6or more carbon atoms or a fluoroalkyl group optionally containing one ormore etheric oxygen atoms and preferably 6 or more carbon atoms.

In one embodiment B and B⁶ may be the same.

Particular examples of preferred monomers bearing a group containing acentre of permanent positive charge are 2 (methacryloyloxy)ethyl-2'(trimethylammonium) ethyl phosphate inner salt and 1(4(4'-vinylbenzyloxy)butane!-2"(trimethylammonium)ethyl phosphate innersalt.

Monomers bearing a group containing a centre of permanent positivecharge, such as those of formula (II) and (III) may be prepared byconventional techniques using known reactions, for example using asuitable substituted alkyl (alk)acrylate or suitable substituted styreneas precursor. Examples of suitable substituted alkyl (alk)acrylatesinclude dimethylaminoethyl(meth)acrylate and 2-hydroxyethyl (meth)acrylate.

Monomers of formula (II) or (III) containing a group of formula (IVA)may be prepared by known methods. Monomers containing a group of formula(IVB) or (IVC) may be prepared as described in Reference Example 1 to 3or by analogous known methods.

Monomers of formula (II) or (III) containing a group of formula (IVD) inwhich R^(3a) is --C(O)B¹ R^(3b) may be prepared by selective acylationof glycerophosphorylcholine or analogues thereof at the primary hydroxylgroup with an activated acid derivative such as an acid anhydrideO(C(O)B¹ R^(3b))₂ or an acid halide R^(8b) B¹ BCOHal where B¹ and R^(8b)are as defined above and Hal is halogen, followed by acylation of thesecondary hydroxyl group with an appropriate acylating agent, forexample methacryloyl chloride. Purification, for example by columnchromatography on a suitable support, may be performed after eachacylation or after the second acylation only. Suitable activated acidderivatives include acid anhydrides, acid halides, reactive esters andimidazolides. The acylations may be performed in a suitable anhydrous,aprotic solvent, for example N,N-dimethylformamide, optionally in thepresence of a suitable non-nucleophilic base, for example triethylamine.

Alternatively, the primary alcohol group in glycerophosphoryl choline oran analogue thereof may be blocked by reaction with a suitableprotecting group reagent, for example t-butyldimethylsilyl chloride,under standard conditions and the secondary hydroxy group then treatedwith an acylating agent such as methacryloyl chloride. Thet-butyldimethylsilyl protecting group may be removed by treatment with adilute organic or mineral acid, for example p-toluene sulphonic acid,hydrochloric acid or with tetra-butylammonium fluoride. The deblockedprimary hydroxyl group may then be treated with an activated acidderivative such as an acid anhydride O(C(O)B¹ R^(8b))₂ or acid halideR^(8b) B¹ COHal where B¹ and R^(8b) are as defined above, and Hal ishalogen.

Analogues of glycerophosphorylcholine (compounds of formual (II) or(III) containing a group (IVD) where R^(8a) is hydrogen) may be preparedby reaction of phosphorus oxychloride with a bromoalcohol in an inertaprotic solvent, such as dichloromethane, to give abromoalkylphosphorodichloridate. The dichloro derivative thus producedmay then be treated with an appropriately protected glycerol derivative,for example 2,2-dimethyl 1,3-dioxolane-4-methanol, in the presence of abase, for example triethylamine, followed by acid hydrolysis to give abromoalkylphosphoro-glycerol derivative. This may then be treated withan amine NR⁸ ₃ ₁ where R⁸ is as defined above, for exampletrimethylamine, to generate the glycerophosphorylcholine analogue. Thispreparation is depicted in the following scheme. ##STR11## where R⁸ andf are as defined in relation to groups of formula (IVD).

Monomers of formula (II) or (III) containing a group of formula (IVE) inwhich R^(9a) is --C(O)B² R^(9b) may be prepared by the selectiveacylation of glycerophosphorylcholine or an analogue thereof at theprimary hydroxyl group with for example, methacryloyl chloride followedby reaction at the secondary hydroxyl group using an activated acidderivative, such as an acid halide O(C(O)B² R^(9b))₂ or an acid halideR^(9b) B² COHal, where B² and R^(9b) are as defined above and Hal ishalogen. The intermediates and final products may be purified, asnecessary using column chromatography. Optionally, protecting groupstrategy, similar to that outlined above in relation to production ofmonomers containing a group of formula (IVD) may be employed.

Monomers of formula (II) or (III) containing a group of formula (IVF)may be prepared in an analogous manner to monomers containing groups offormula (IVD) or (IVE).

Monomers of formula (II) or (III) containing a group of formula (VA),(VB) or (VC) may be prepared by direct analogy with methods describedfor monomers containing groups of formula (IVD), (IVE) and (IVF)respectively.

Comonomers Capable of Stably Binding a Polymer to a Surface

In the polymer of the invention, where the group bearing a centre ofpermanent positive charge and group capable of stably binding thepolymer to a surface are not present in the residue of the same monomer,the polymer comprises residues of comonomer containing a group capableof stably binding a polymer to a surface as well as the residues of thecomonomer containing a group bearing a centre of permanent positivecharge. Optionally, where the monomer containing a group bearing acentre of permanent positive charge also contains a group capable ofstably binding the polymer to a surface, further groups capable ofstably binding to a surface may be provided by additional comonomerresidues containing a group capable of binding the polymer to a surface.

As has already been mentioned, the nature of the group capable ofbinding to a surface, and therefore the nature of the comonomerscontaining such groups, will depend upon the nature of the surface whichis to be coated with the polymer. The various types of such comonomerswill now be described.

It will be appreciated that in some circumstances it may be desirable touse a combination of different comonomers containing groups capable ofbinding to a surface. Preferably a comonomer of type a), b) and/or c) asdefined below or a combination of such comonomers is used, morepreferably only one of comonomer types a), b) and c) is used.

a) Comonomers containing an alkyl, fluoroalkyl or siloxane group

The comonomers containing an alkyl, fluoroalkyl or siloxane group, whichare suitable for providing binding to a hydrophobic surface, arecomonomers containing an alkyl group of 6 or more carbon atoms whichgroup optionally contains one or more etheric oxygen atoms andoptionally one or more carbon-carbon double or triple bonds or afluoroalkyl group, preferably of 6 or more carbon atoms, which groupoptionally contains one or more etheric oxygen atoms and optionally oneor more carbon-carbon double or triple bonds, or containing a siloxanegroup, containing up to 50 silicon atoms, preferably in a linear chain.

Preferably the alkyl or fluoroalkyl groups contains up to 24 carbonatoms, for instance up to 18 carbon atoms, or containing a siloxanegroup, containing up to 50 silicon, preferably in a linear chain.Preferred comonomers containing an alkyl, fluoroalkyl or siloxane groupare those of general formula (VI)

    Y.sup.1 --Q                                                (VI)

where Y¹ is an ethylenically unsaturated polymerisable group selectedfrom ##STR12## where R¹⁴ is hydrogen or C₁ -C₄ alkyl, A' is --O-- or--NR¹⁵ -- where R¹⁵ is hydrogen or a C₁ -C₄ alkyl group or R¹⁵ is agroup Q;

K¹ is a group --(CH₂)₁ OC(O)--, --(CH)₁ C(O)O--, --(CH₂)₁ OC(O)O--,--(CH₂)₁ NR¹⁶ --, --(CH₂)₁ NR¹⁶ C(O)--, --(CH₂)₁ C(O) NR¹⁶ --, --(CH₂)₁NR¹⁶ C(O)O--, --(CH₂)₁ OC(O)NR¹⁶ --, --(CH₂)₁ INR¹⁶ C(O) NR¹⁶ -- (inwhich the groups R¹⁶ are the same or different), --(CH₂)₁ O--, --(CH₂)₁SO₃ --, a valence bond and 1 is from 1 to 12 and R¹⁶ is hydrogen or a C₁-C₄ alkyl group; and

Q is (a) a straight or branched alkyl, alkoxyalkyl or(oligo-alkoxy)alkyl chain containing 6 or more, preferably 6 to 24,carbon atoms unsubstituted or substituted by one or more fluorine atomsand optionally containing one or more carbon-carbon double or triplebonds; or

(b) a siloxane group --(CR^(16a) ₂)_(qq) (SiR^(16b) ₂) (OSiR^(16b)₂)_(pp) R^(16b) in which each group R^(16a) is the same or different andis hydrogen or alkyl of 1 to 4 carbon atoms or aralkyl, for examplebenzyl or phenethyl, each group R^(16b) is alkyl of 1 to 4 carbon atoms,qq is from 1 to 6 and pp is from 0 to 49.

Preferred comonomers of formula (VI) bearing a group Q include those offormula (VII) and (VIII): ##STR13## wherein: R¹⁴, A', K¹ and Q are asdefined in relation to formula (VI).

Preferably in the compounds of formula (VII) R¹⁴ is hydrogen methyl orethyl, more preferably methyl so that the compound of formula (VII) ispreferably an acrylic acid, methacrylic acid or ethacrylic acidderivative.

In the compounds of formula (VIII) K¹ may for instance be a valencebond. Where K¹ is a group then preferably 1 is from 1 to 6, morepreferably 1, 2 or 3 and most preferably 1 is 1. When K¹ is a group--(CH₂)₁ NR¹⁶ --, --(CH₂)₁ OC(O)NR¹⁶ --, --(CH₂)₁ NR¹⁶ C(O)O--, --(CH₂)₁NR¹⁶ C(O)--, --(CH₂)₁ C(O)NR¹⁶ -- or --(CH₂)₁ NR¹⁶ C(O)NR¹⁶ -- then R¹⁶is preferably hydrogen, methyl or ethyl, more preferably hydrogen.

In the compounds of formula (VIII), preferably the vinyl group is parato the group --K¹ --Q.

Preferably Q is an alkyl or fluoroalkyl group optionally containing oneor more etheric oxygen atoms and optionally one or more carbon-carbondouble or triple bonds. More preferably Q is:

an alkyl group of formula --(CR¹⁷ ₂)_(m) CR¹⁷ ₃, wherein the groups--(CR¹⁷ ₂)-- are the same or different, and in each group --(CR¹⁷ ₂)--the groups R¹⁷ are the same or different and each group R¹⁷ is hydrogen,fluorine or C₁₋₄ alkyl or fluoroalkyl and m is from 5 to 23 if Qcontains no fluorine atoms or from 1 to 23, preferably 5 to 23, if Qcontains one or more fluorine atoms;

an alkoxyalkyl having 1 to 12 carbon atoms in each alkyl moiety;unsubstituted or substituted by one or more fluorine atoms; or

an (oligo-alkoxyl) alkyl group of formula -- (CR¹⁸ ₂)_(s) O!_(o) (CR¹⁸₂)_(s) R¹⁸ where the groups --(CR¹⁸ ₂)-- are the same or different andin each group --(CR¹⁸ ₂)-- the groups R¹⁸ are the same or different andeach group R¹⁸ is hydrogen, fluorine or C₁₋₄ alkyl or fluoroalkyl and nis from 2 to 6, preferably 3 to 4, and o is from 1 to 12.

When Q is a group -- (CR¹⁸ ₂)_(s) O!_(o) (CR¹⁸ ₂)_(s) R¹⁸ wherein allthe groups R¹⁸ are hydrogen and in all the groups -- (CR¹⁸ ₂)_(s) O!-- nis 2 the group of formula Q is not able to form strong secondary valenceinteractions with hydrophobic surfaces. Whilst residues of monomerscontaining such a group may be included in the polymers of theinvention, it is also necessary to include residues of monomers whichare capable of forming such strong secondary valence interactions ifsuch interactions are to bind a polymer to a surface. Monomers whichhave groups containing oligo(higher alkylene) oxide moieties can be usedto provide monomers which contain oligo alkylene oxide moieties in whichat least 50mol % of individual alkylene oxide units contain 3 or morecarbons atoms. Thus, for instance a mixed oligo(ethylene oxide/propyleneoxide) side chain could be used provided that there are more propyleneoxide units than ethylene oxide units.

Where Q is an (oligo-alkoxy)-alkyl group containing residues -- (CR¹⁸₂)_(s) O!-- wherein n is 2, then preferably n is 2 in no more than 50mol % of the residues -- (CR¹⁸ ₂)_(s) O!--.

Alternatively, Q may be a group in which one or more of the alkyl oralkylene moieties in such an alkyl, alkoxyalkyl or (oligoalkoxy) alkylgroup is replaced by a corresponding alkenyl, alkynyl, alkenylene oralkynylene moiety.

Preferred groups Q include alkyl, alkoxyalkyl and (oligo-alkoxy)alkylgroups optionally containing one or more carbon-carbon double or triplebonds of 8 or more, more preferably 10 or more, even more preferably 12or more, for instance 14 or more, such as 16 or more carbon atoms. Suchgroups may contain one or more fluorine atoms and be thereforefluoroalkyl derivatives. Preferably however, such groups do not containany fluorine atoms.

Particularly preferred groups are straight chain alkyl or fluoroalkylgroups optionally containing one or more carbon-carbon double or triplebonds.

Where Q is a siloxane group, each group --(CR^(16a) ₂)-- may be the sameor different, preferably the same, and preferably each group R^(16a) ishydrogen. Preferably qq is from 2 to 4, and is most preferably 3. Eachgroup --(SiR^(16b) ₂)-- may be the same or different, preferably thesame, and preferably each group R^(16b) is methyl. Preferably pp is from4 to 29. Preferred comonomers where Q is a siloxane group are those offormula (VII).

In one specific embodiment the group Q does not contain any ethylenicunsaturation, i.e. any carbon-carbon double or triple bonds.

Particular examples of comonomers containing an alkyl, fluoroalkyl orsiloxane group include: n-dodecyl methacrylate, octadecyl methacrylate,hexadecyl methacrylate, 1H,1H,2H,2H-heptadecafluorodecyl methacrylate,p-octyl styrene, p-dodecyl styrene and monomethacryloxypropyl terminatedsiloxanes. n-Dodecyl methacrylate is particularly preferred.

Comonomers containing a physisorbable alkyl or fluoroalkyl, which doesnot contain a carbon-carbon double or triple bond, or a siloxane groupsuch as those of formulae (VII) and (VIII) are commercially available ormay be prepared by conventional techniques using known reactions.

In a second specific embodiment of such comonomers, the group Q doescontain ethylene unsaturation, i.e. one or more carbon-carbon double ortriple bonds. Such comonomers may for example contain a vinylic,divinylic, acetylenic or diacetylenic moiety. Comonomers containingacetylenic rather than vinylic unsaturation are in general preferred,especially those containing a single acetylenic group.

Comonomers which contain such an ethylenic unsaturated group are capableof providing crosslinking between linear polymer claims once the polymeris coated onto a substrate, as well as binding to the substrate byphysisorption. Such crosslinking may improve the stability of thecoating and is typically formed by irradiation, for example with UV-orgamma-radiation. The crosslinking of such groups may be employed eitheralone or in addition to the use of a comonomer containing a reactivegroup as a crosslinkable comonomer as described below.

Particularly preferred crosslinkable comoners capable of binding to asubstrate by physisorption are those of formula (VIIA) and (VIIIA)##STR14## in which R¹⁴, A' and K¹ are as hereinbefore defined and QQ isan alkynyl group containing 6 or more carbon atoms and one or two,preferably one, carbon-carbon triple bonds provided that the acetylenicmoieties are not directly bonded to A' or K¹.

The present invention provides, as a further feature, comonomers offormula (VIIA) and (VIIIA).

Amongst such comonomers it is preferred that QQ is a group containingfrom 6 to 24 carbon atoms, preferably 8 or more, more preferably 10 ormore, even more preferably 12 or more, for instance 14 or more, such as16 or more carbon atoms.

It is also preferred that the group QQ does not contain a terminalacetylenic moiety, i.e. a group --C.tbd.CH.

A particularly preferred group QQ is 7-dodecynyl and a specific exampleof a compound of formula (VIIA) containing such a group isdodec-7-yn-1-ol methacrylate.

The compound of formula (VIIA) and (VIIIA) and other comonomers offormula (VII) and (VIII) containing an ethylenically unsaturatedphysisorable group Q, may be prepared by anology with known methods.Their preparation is illustrated by Reference Example 5.

b) Comonomers bearing a reactive group

Preferred comonomers, which are suitable for providing binding to ahydrophilic surface having functional groups, contain a reactive groupcapable of covalently binding to a surface and are of general formula(IX)

    Y.sup.2 --Q.sup.1                                          (IX)

where Y² is an ethylenically unsaturated polymerisable group selectedfrom ##STR15## where R¹⁹ is hydrogen or C₁ -C₄ alkyl, K² is a group--(CH₂)_(q) OC(O)--, --(CH)_(q) C(O)O--, --(CH₂)_(q) OC(O)O--, 13(CH₂)_(q) NR²⁰ --, --(CH₂)_(q) NR²⁰ C(O) --, --(CH₂)_(q) C(O)NR²⁰ --,--(CH₂)_(q) NR²⁰ C(O)O--, --(CH₂)_(q) OC(O)NR²⁰ --, --(CH₂)_(q) NR²⁰C(O)NR-- (in which the groups R²⁰ are the same or different),--(CH₂)_(q) O--, or --(CH₂)_(q) SO₃ --, or a valence bond and q is from1 to 12 and R²⁰ is hydrogen or a C₁ -₄ alkyl group; and

Q¹ is a reactive group capable of reacting to provide covalent bindingto a surface.

Preferred comonomers of formula (IX) bearing a reactive group Q¹ includethose of formula (X) and (XI) defined below.

The compounds of formula (X) are: ##STR16## wherein: R¹⁹ is as definedwith reference to formula (X) , and Q² is a reactive group.

Preferably in the compounds of formula (X) R¹⁹ is hydrogen, methyl orethyl, more preferably methyl, so that the compound of formula (X) ispreferably an acrylic acid, methacrylic acid or ethacrylic acidderivative.

Preferably Q² is hydrogen, or more preferably --OH or a group of theformula:

    --T--B.sup.7 --Q.sup.3

where

T is --O--, or --NR²¹ where R²¹ is hydrogen, C₁ -C₄ alkyl or a group--B⁷ --Q³ ;

B⁷ is a valence bond or, more preferably, a straight or branchedalkylene, oxaalkylene or oligo-oxaalkylene chain; and

Q³ is a reactive group capable of reacting to provide covalent bindingto a surface such as an aldehyde group or a silane or siloxane groupcontaining one or more reactive substituents such as halogen, forexample chlorine, or alkoxy, generally containing from 1 to 4 carbonatoms, for example methoxy or ethoxy, or, more preferably Q³ is ahydroxyl, amino, carboxyl, epoxy, --CHOHCH₂ Hal, (in which Hal is ahalogen atom such as chlorine, bromine or iodine) succinimido, tosylatesuch as 2(N-methylpyridinium) tosylate, triflate, imidazolecarbonyl-amino, or an optionally substituted triazine group.

Preferably B⁷ is:

an alkylene group of formula --(CR²² ₂),--, wherein the groups --(CR²²₂)-- are the same or different, and in each group --(CR²²)-- the groupsR²² are the same or different and each group R²² is hydrogen or C₁₋₄alkyl, preferably hydrogen, and r is from 1 to 12, preferably 1 to 6;

an oxaalkylene group such as alkoxyalkyl having 1 to 6 carbon atoms ineach alkyl moiety; or

an oligo-oxaalkylene group of formula -- (CR²³ ₂)_(s) O!_(t) (CR²³₂)_(s) -- where the groups --(CR²³ ₂)-- are the same or different and ineach group --(CR²³ ²)-- the groups R²³ are the same or different andeach group R²³ is hydrogen or C₁₋₄ alkyl, preferably hydrogen, and s isfrom 1 to 6, preferably 2 or 3, and t is from 1 to 11, preferably 1 to5.

Preferred groups B⁷ include alkylene, oxaalkylene and oligo-oxaalkylenegroups of up to 12 carbon atoms.

Where Q³ is a silane or siloxy group, preferably B⁷ is an alkylene groupof 1 to 6, preferably 2 to 4, more preferably 3 carbon atoms.

Particular examples of the group B⁷ are --CH₂ --, --CH₂ CH₂ -- and--(CH₂)₆ --.

The compounds of formula (XI) are: ##STR17## wherein K² is as defined inrelation to formula (IX) and;

B⁸ is a straight of branched alkylene, oxaalkylene or oligo-oxaalkylenechain and

Q⁴ is a reactive group capable of reacting to provide covalent bindingto a surface, for example an aldehyde group or a silane or siloxanegroup containing one or more reactive substituents such as halogen, forexample chlorine, or alkoxy, generally containing from 1 to 4 carbonatoms, for example methoxy or ethoxy, or, more preferably, Q⁴ is ahydroxyl, amino, carboxyl, epoxy, --CHOHCH₂ Hal, (in which Hal is ahalogen atom such as chlorine, bromine or iodine) succinimido, tosylate,triflate, imidazole carbonyl-amino or optionally substituted triazinegroup.

In the compounds of formula (XI) preferably the vinyl group is para tothe group --K² --B⁸ --Q⁴.

K² may for instance be a valence bond. Where K² is a group thenpreferably q is from 1 to 6, more preferably 1,2 or 3 and mostpreferably q is 1. When K² is a group --(CH₂)_(q) NR²⁰ --, --(CH₂)_(q)OC(O)NR²⁰ --, --(CH₂)_(q) NR²⁰ C(O)O--, --(CH₂)_(q) NR²⁰ C(O)--,--(CH₂)_(q) C(O)NR²⁰ -- or (CH₂)_(q) NR²⁰ C(O)NR²⁰ -- then R²⁰ ispreferably hydrogen, methyl or ethyl, more preferably hydrogen.

Preferably B⁸ is;

an alkylene group of formula --(CR²⁴ ₂)_(u) --, wherein the groups;--(CR²⁴ ₂)-- are the same or dif ferent, and in each group --(CR²⁴ ₂)--the groups R²⁴ are the same of different and each group R²⁴ is hydrogenor C₁₋₄ alkyl, preferably hydrogen, and u is from 1 to 12, preferably 1to 6;

an oxaalkylene group such as alkoxyalkyl having 1 to 6 carbon atoms ineach alkyl moiety; or

an oligo-oxaalkylene group of formula -- (CR²⁵ ₂)_(v) O!_(w) (CR²⁵)_(v)-- where the groups --(CR²⁵ ₂)-- are the same or different and in eachgroup --(CR²⁵ ₂)-- the groups R²⁵ are the same or different and eachgroup R²⁵ is hydrogen or C₁₋₄ alkyl, preferably hydrogen, and v is from1 to 6, preferably 2 or 3, and w is from 1 to 12, preferably 1 to 6.

Preferred groups B⁸ include alkylene, oxaalkylene and oligo-oxaalkylenegroups of up to 12 carbon atoms. In one embodiment B⁸ and K² containtogether up to 12 carbon atoms.

Particular examples of comonomers bearing a reactive group includechloromethylstyrene, methacrylic acid, 2-aminoethylmethacrylate,2,3-epoxypropyl methacrylate, 3-chloro-2-hydroxypropylmethacrylate,2-methacryloyloxy- ethyl dichlorotriazine,3-chloro-2-hydroxy-propylmethacrylamide and glycidyl methacrylate andreactive methacrylate esters containing the group HetC(O)O-- in which(Het) is a heterocyclic ring, for example benzotriazole or imidazole andreactive methacrylate esters containing a group R¹⁶ OC(O)-- in which R¹⁶is a succinimido or pentafluorophenyl group.

Particularly preferred comonomers bearing reactive groups are2-aminoethyl-methacrylate and 3-chloro-2-hydroxypropylmethacrylate.

Comonomers bearing a reactive group capable of binding covalently to asurface, such as those of formula (X) or (XI), are commerciallyavailable or may be prepared by conventional techniques using knownreactions.

Comonomers of formula (X), which are dichlorotriazine monomers may beprepared in known manner for example by reacting a substitutedhydroxy-alkyl(alk)acrylate or aminoalkyl(alk)acrylate withtrichlorotriazine in a suitable solvent and in the presence of a base.

Comonomers of formula (XI) which are reactive methacrylate esters inwhich the ester groups contains an imidazole group may be prepared inknown manner by reacting a substituted hydroxyalkyl(alk)acrylate (e.g.2-hydroxyethyl-(meth)acrylate), polyethylene-oxide(meth)acrylate orpolypropyleneoxide (meth)acrylate with 1,1-carbonyl-diimidazole in a drysolvent. Analogous known methods may be used to prepare succinimido andpentafluorophenyl methacrylate esters of formula (X), by reaction with areactive ester, acid halide or acid anhydride.

Where comonomers containing a reactive group are used to bind acopolymer to a surface by covalent bonding, it will be appreciated thatnot all of the reactive groups need necessarily bind to surface reactivegroups and that groups not so bound may participate in other chemistry.Such groups may in particular provide points for the attachment ofmoieties such as ligands to the polymer, when coated onto a substrate.

Comonomers containing a reactive group, such as compounds of formula (X)and (XI) may be used as comonomers containing crosslinkable groups,which react with other crosslinkable groups, rather than a monomer whichbind covalently to a surface.

Where comonomers containing a reactive group are used to provide suchcrosslinkable groups then the crosslinkable groups and/or thecopolymerisation conditions will be chosen so that they will notcrosslink when the comonomers are copolymerised; thus the polymerisationproduct will be an uncrosslinked linear copolymer which may besubsequently crosslinked after coating the copolymer onto a surface soas to improve the stability of the coating. When such crosslinkingbetween linear polymer chains is employed the crosslinkage may be formedeither between two such crosslinkable groups or between a crosslinkablegroup and a non-inert group in a diluent comonomer residue (definedlater). Such a crosslinkage may be formed either by direct reaction ofthe groups forming the crosslinkage or by reaction of these groups witha reactive bridging molelcule for example a reactive gas, such asammonia.

Residues of such comonomers may therefore be present in polymers whichare designed to coat hydrophobic surfaces and containing residues of amonomer containing a group bearing a centre of permanent positive chargewhich is of formula (VA), (VB) or (VC) or a comonomer containing analkyl, fluoroalkyl or siloxane group, which is of formula (VII) or(VIII). Similarly residues of such comonomers may also be present inpolymers designed to bind to a surface by ionic interaction and whichcontains residues of a compound of formula (XIII) or (XIV) as definedbelow.

Preferred reactive comonomers which are used to crosslink the comonomer,rather than provide covalent binding to the surface, are those offormula (X) or (XI) in which Q², or Q⁴ contains a crosslinkablecinnamyl, epoxy, --CHOHCH₂ Hal (in which Hal is a halogen atom),methylol, silyl, an ethylenically unsaturated crosslinkable group, suchas an acetylenic, diacetylenic, vinylic or divinylic group, or anacetoacetoxy or chloroalkyl sulfone, preferably chloroethyl sulphone,group.

Particular examples of comonomers bearing a group capable ofcrosslinking include methacrolein, cinnamyl methacrylate,2,3-epoxypropyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate,hydroxymethyl methacrylamide, 3-(trimethoxysilyl)propyl methacrylate,2-acetoacetoxyethyl methacrylate, 3-(vinylbenzyl)-2-chloroethyl sulfone.

When a polymer of the invention, containing crosslinkable groups, iscoated on a substrate the polymer is in substantially uncrosslinkedform. After coating, crosslinking of crosslinkable groups may beperformed to increase the strength and stability of the polymer coating.

c) Comonomers bearing an ionic group

Preferred comonomers bearing an ionic group capable of binding to asurface by ionic interaction are of general formula (XII)

    Y.sup.2 --B.sup.9 --Q.sup.5                                (XII)

where Y² is an ethylenically unsaturated polymerisable group selectedfrom ##STR18## where R²⁶ is hydrogen or C₁ -C₄ alkyl; A" is --O--or--NR²⁷ --, wherein R²⁷ is hydrogen or a C₁ -C₄ alkyl group or R²⁷ is agroup --B⁹ --Q⁵ ;

B⁹ is a valence bond, a straight or branched alkylene, oxaalkylene oroligo-oxaalkylene group;

K³ is a group --(CH₂)_(x) OC(O)--, --(CH)_(x) C(O)O--, --(CH₂)_(x)OC(O)O--, --(CH₂)_(x) NR²⁸ --, --(CH₂)_(x) NR²⁸ C(O)--, --(CH₂)_(x)C(O)NR²⁸ --, --(CH₂)_(x) NR²⁸ C(O)O--, --(CH₂)_(x) OC(O)NR²⁸ --,--(CH₂)_(x) NR²⁸ C(O)NR²⁸ -- (in which the groups R²⁸ are the same ordifferent), --(CH₂)_(x) O--, --(CH₂)_(x) SO₃ --, a valence bond(optionally in combination with B9) and x is from 1 to 12 and R²⁸ ishydrogen or a C₁ -C₄ alkyl group;

Q⁵ is an ionic group capable of binding to a surface by ionicinteraction.

Preferred comonomers of formula (XII) are therefore those of formula(XIII) and (XIV): ##STR19## wherein: R²⁶, A", B⁹, K³ and Q⁵ are asdefined in relation to formula (XII).

Preferably in the compounds of formula (XIII) R²⁶ is hydrogen, methyl orethyl, more preferably methyl, so that the compound of formula (XIII) ispreferably an acrylic acid, methacrylic acid or ethacrylic acidderivative.

In the compounds of formula (XIV), K³ may for instance be a valencebond. Where K³ is a group then x is preferably from 1 to 6, morepreferably 1, 2 or 3 and most preferably x is 1. When K³ is a group--(CH₂)_(x) NR²⁶ --, --(CH₂)_(x) OC(O)NR²⁶ --, --(CH₂)_(x) NR²⁶ C(O)O--,--(CH₂)_(x) NR²⁶ C(O)--, --(CH₂)_(x) C(O)NR²⁶ -- or --(CH₂)_(x) NR²⁶C(O)NR²⁶ -- then R²⁶ is preferably hydrogen, methyl or ethyl, morepreferably hydrogen.

In the compounds of formula (XIV) preferably the vinyl group is para tothe group --K³ --B⁸ --Q⁴.

Preferably B⁹ is:

an alkylene group of formula --(CR²⁹)_(y) --, wherein the groups --(CR²⁹₂)-- are the same or different, and in each group --(CR²⁹ ₂)-- thegroups R²⁹ are the same or different and each group R²⁹ is hydrogen orC₁₋₄ alkyl, preferably hydrogen, and y is from 1 to 12, preferably 1 to6;

an oxaalkylene group such as alkoxyalkyl having 1 to 6 carbon atoms ineach alkyl moiety; or

an oligo-oxaalkylene group of formula -- (CR³⁰ ₂)_(yy) O!_(xx) (CR³⁰₂)_(yy) -- where the groups --(CR³⁰ ₂)-- are the same or different andin each group --(CR³⁰ ₂)-- the groups R³⁰ are the same or different andeach group R³⁰ is hydrogen or C₁₋₄ alkyl, preferably hydrogen, and yy isfrom 1 to 6, preferably 2 or 3, and xx is from 1 to 12, preferably 1 to6.

Preferred groups B⁹ include alkylene, oxaalkylene and oligo-oxaalkylenegroups of up to 12 carbon atoms.

Particular examples of the group B⁹ are --CH₂ --, --CH₂ CH₂ -- and--(CH₂)₆ --.

The group Q⁵ may be either anionic or cationic depending pon the surfaceto be coated. Where the surface has a cationic surface charge, the groupQ⁵ will be anionic and may for example be a carboxylate, sulphonate,hydrogenphosphate or phosphate group. Where the surface has an anionicsurface charge, the group Q⁵ will be cationic and may for example by agroup --NR³¹ ₃.sup.⊕ in which each group R³¹ is the same or different,and is hydrogen or alkyl of 1 to 6 carbon atoms two of which groups R³¹may together from a heterocyclic ring containing from 5 to 7 atoms,preferably hydrogen or methyl, a group N.sup.⊕ Het, where Het is anunsaturated heterocyclic group such as pyridyl, substituted orunsubstituted by one or more alkyl groups of 1 to 4 carbon atoms, or agroup --PR³² ₃.sup.⊕ in which each group R³² is the same or differnt andis hydrogen or alkyl of 1 to 6 carbons atoms, two of which groups R³¹may together form a heterocyclic ring containing from 5 to 7 atoms,preferably methyl.

Particular examples of comonomers bearing an ionic group include acrylicacid, methacrylic acid, 2-sulfoethyl methacrylate,2-methacryloyloxyethyl phosphate, p-styrene sulfonic acid,2-(methacryloyloxyethyl)trimethylammonium chloride, 3-aminopropylmethacrylamide, vinylbenzyl trimethylammonium chloride.

Comonomers bearing a group capable of binding a polymer to a surface byionic interaction, such as those of formula (XIII) and (XIV) arecommercially available or may be prepared by conventional techniquesusing known reactions.

Diluent Comonomers

In addition to a) the residues of monomers containing a group bearing acentre of permanent positive charge or b) the residues of comonomerscontaining a group bearing a centre of permanent positive charge andcomonomers which are capable of binding to a surface, the polymers ofthe present invention may comprise residues of a diluent comonomer.

Such diluent comonomers may be used to give the polymer the desiredphysical and mechanical properties. They may be of any knownconventional radical polymerisable, preferably ethylenicallyunsaturated, type compatible with other comonomer(s).

Particular examples of diluent comonomers include alkyl(alk)acrylatepreferably containing 1 to 4 carbon atoms in the alkyl group of theester moiety, such as methyl (alk)acrylate; a dialkylaminoalkyl(alk)acrylate, preferably containing 1 to 4 carbon atoms in eachalkyl moiety of the amine and 1 to 4 carbon atoms in the alkylene chain,e.g. 2-(dimethylamino)ethyl (alk)acrylate; an alkyl (alk)acrylamidepreferably containing 1 to 4 carbon atoms in the alkyl group of theamide moiety; a hydroxyalkyl (alk)acrylate preferably containing from 1to 4 carbon atoms in the hydroxyalkyl moiety, e.g. a 2-hydroxyethyl(alk)acrylate; or a vinyl monomer such as an N-vinyl lactam, preferablycontaining from 5 to 7 atoms in the lactam ring, for instance vinylpyrrolidone; styrene or a styrene derivative which for example issubstituted on the phenyl ring by one or more alkyl groups containingfrom 1 to 6, preferably 1 to 4, carbon atoms, and/or by one or morehalogen, such as fluorine atoms, e.g. (pentafluorophenyl)styrene.

Other suitable diluent comomers include polyhydroxyl, for example sugar,(alk)acrylates and (alk)acrylamides in which the alkyl group containsfrom 1 to 4 carbon atoms, e.g. sugar acrylates, methacrylates,ethacrylates, acrylamides, methacrylamides and ethacrylamides. Suitablesugars include glucose and sorbitol. Particularly suitable diluentcomonomers include methacryloyl glucose or sorbitol methacrylate.

Further diluents which may be mentioned specifically includepolymerisable alkenes, preferably of 2-4 carbon atoms, eg. ethylene,dienes such as butadiene, alkylene anhydrides such as maleic anhydrideand cyano-substituted alkylenes, such as acrylonitrile.

Diluent comonomers may be obtained by conventional known methods.

Of the above diluent comonomers some are inert and act simply to modifythe physical and mechanical properties of copolymers containing them.Others, and in particular the hydroxyalkyl(alk)acrylates andpolyhydroxyl (alk)acrylates have a reactive role in addition to simplymodifying physical and mechanical properties. Such comonomers containfunctional groups, such as hydroxyl groups, which may react with acrosslinking group or may react with reactive groups in other moleculesto attach them to the copolymer.

It will also be appreciated that alkyl(alk)acrylates containing 6 ormore carbon atoms in the alkyl group may be regarded as either diluentcomonomers or comonomers capable of binding a polymer to a surface byphysisorption. In particular it should be noted that a copolymer whichcontains such a diluent comonomer and a reactive comonomer capable ofreacting at a surface to provide covalent binding to a surface may beused to coat a hydrophilic surface, the reactive comonomer rovidingbinding to the surface and the diluent modifying hysical and mechanicalproperties. However, such a copolymer may also be to coat hydrophobicsurfaces, in which the "diluent" monomer will act as a comonomer capableof binding to the surface by physisorption and the comonomer capable ofcovalent binding will act as a crosslinkable comonomer.

According to a feature of the present invention polymers of theinvention may be prepared by:

a) copolymerising a comonomer containing a group bearing a centre ofpermanent positive charge, preferably a zwitterionic group, a comonomercontaining a group capable of stably binding the polymer to a surfaceand optionally a diluent and/or crosslinkable comonomer; or

b) polymerising a monomer containing a group containing a group bearinga centre of permanent positive charge, preferably a zwitterionic group,and a group capable of stably binding the polymer to a surface andoptionally further comonomer containing a group capable of stablybinding the polymer to the surface and a diluent and/or a crosslinkablecomonomer.

Any conventional technique may be used for polymerisation, typicallythermal or photochemical polymerisation. Where comonomers capable ofproducing crosslinking in the coated polymer film are present, thepolymerisation condition are set such that crosslinking does not occurduring polymerisation. Thus, for example, actinic radiation would not beused to prepare a polymer containing a comonomer which can formcrosslinks by exposure to actinic radiation.

For thermal polymerisation a temperature from 40 to 100° C., typically50° to 80° C. is used. For photochemical polymerisation actinicradiation such as gamma, U.V., visible, or microwave radiation may beused. Typically U.V. radiation of wavelength 200 to 400 nm is used.

The polymerisation is generally performed in a reaction medium, which isfor instance a solution or dispersion using as a solvent for exampleacetonitrile, dimethyl formamide, chloroform, dichloromethane, ethylacetate, dimethyl sulphoxide, dioxan, benzene, toluene, tetrahydrofuran,or where the polymer does not contain groups which react with proticsolvents, water or an alkanol containing from 1 to 4 carbon atoms, e.g.methanol, ethanol or propan-2-ol. Alternatively, a mixture of any of theabove solvents may be used.

The polymerisation may be carried out in the presence of one or morepolymerisation initiators, such as benzoyl peroxide,2,2'-azo-bis(2-methylpropionitrile) or benzoin methyl ether. Otherpolymerisation initiators which may be used are disclosed in "PolymerHandbook", 3rd edition, Ed. J. Brandrup and E. H. Immergut, Pub.Wiley-Interscience, New York, 1989.

Generally the copolymerisation is performed for 1 to 72 hours,preferably 8 to 48, for instance 16 to 24 hours, and under an inertatmosphere of for example nitrogen or argon. The polymer is generallypurified by dialysis, precipitation in a non-solvent (e.g. diethyl etheror acetone) or ultrafiltration. The resulting polymer is generally driedunder vacuum, eg. for 5 to 72 hours and has a molecular weight from10,000 to 10 million, preferably from 20,000 to 1 million.

The precise proportion and nature of the various comonomers used toprepare a copolymer according to the present invention comprisingresidues of a comonomer containing a group bearing a centre of permanentpositive charge and a comonomer containing a group capable of stablybinding the polymer to a surface may be adjusted to provide a copolymerwhich is particularly suitable for coating a particular surface. Thusthe proportion of comonomer containing a group capable of stably bindingthe polymer to a surface may be adapted to provide efficientphysisorption at a particular hydrophobic surface, to correspond to thenumber of functional groups at a particular surface or to provideefficient binding by ionic interaction with a particular surface.Similarly the proportion of the comonomer containing a group bearing acentre of permanent positive charge and of diluent and/or crosslinkablecomonomer may be adapted to provide the desired biocompatibility andphysical and mechanical properties. It will be appreciated that toobtain the desired combination of properties more than one type ofcomonomer containing a group bearing a centre of permanent positivecharge, comonomer containing a group capable of stably binding thepolymer to a surface or crosslinkable and/or diluent comonomer may beused.

Similarly, in polymers comprising residues of a monomer containing agroup bearing a centre of permanent positive charge and a group capableof stably binding the polymer to a surface, the nature of these groupsmay be adjusted to provide the desired biocompatibility and efficientbinding at a particular surface, as well as desired physical andmechanical properties. Where, in addition, a diluent and/orcrosslinkable comonomer is used the nature of the diluent and/orcrosslinkable comonomer and the proportions of the comonomers may belikewise adjusted. It will again be appreciated that to obtain thedesired combination of properties more than one type of monomercontaining a group bearing a centre of permanent positive charge and agroup capable of stably binding the polymer to a surface and/or morethan one type of crosslinkable and/or diluent comonomer may be used.

The monomer composition which is subjected to polymerisation to providea polymer according to the invention comprises a minimum of 0.01%,preferably 1%, more preferably 5% by weight of monomer or monomerscontaining a group bearing a centre of permanent positive charge and amaximum of 99.9%, preferably 99%, more preferably 95% by weight of othermonomer or monomers. Such other monomer or monomers may be a monomer ormonomers containing a group capable of stably binding the polymer to asurface, a diluent monomer or monomers and/or a crosslinkable monomer ormonomers.

The monomer composition further comprises a minimum of 0.01%, preferably1%, more preferably 5% by weight of monomer or monomers containing agroup capable of stably binding the polymer to a surface and a maximumof 99.9%, preferably 99%, more preferably 95% by weight of other monomeror monomers. Such other monomer or monomers may be a monomer or monomerscontaining a group bearing a centre of permanent positive charge, adiluent monomer or monomers and/or a crosslinkable monomer or monomers.

It will be appreciated that where at least some of the monomer ormonomers containing a group bearing a centre of permanent positivecharge also contains a group capable of stably binding the polymer to asurface, at least a proportion of the content of both these groups isprovided by the same monomer. In such a case the polymer may be ahomopolymer of a monomer containing both these groups.

Where the polymer is to bind to a surface by physisorption thenpreferably the monomer composition comprises no more than 95%, morepreferably no more than 90% and even more preferably no more than 80% byweight of monomer or monomers containing an alkyl, fluoroalkyl orsiloxane group which is capable of binding the polymer to a surface byphysisorption and which does not also contain a group bearing a centreof permanent positive charge, the balance of the composition beingmonomer or monomers containing a group bearing a centre of permanentpositive charge, diluent monomer or monomers and/or crosslinkablemonomer or monomers. Such a composition typically comprises up to 50% byweight of diluent comonomer or comonomers. Where diluent comonomer ispresent, it preferably comprises at least 1t, more preferably 5%, byweight of the total comonomer composition. Where present, crosslinkablecomonomer or comonomers generally comprise from 0.1% to 20% by weight ofthe total comonomer composition.

Where different comonomers are used to provide the centre of permanentpositive charge and the physisorption, then preferably the molar ratioin the copolymer of comonomer residues bearing a centre of permanentpositive charge to comonomer residues containing an alkyl, fluoroalkylor siloxane group capable of binding the polymer to a surface byphysisorption is from 5:95 to 80:20, more preferably 10:90 to 50:50. Inaddition the copolymer preferably comprises from 5% to 50%, morepreferably 10% to 25%, by mole residues of diluent monomer and/or from0.1 to 20%, more preferably 1% to 10%, by mole residues of crosslinkablecomonomer, provided that where residues of both diluent andcrosslinkable comonomer are present, they do not exceed in combination50%, preferably 35% by mole.

Where the polymer is to bind covalently to a surface then preferably themonomer composition comprises no more than 25%, more preferably up to20% and even more preferably up to 15% by weight of monomer or monomerscontaining a group capable of binding the polymer to a surfacecovalently and which does not also contain a group bearing a centre ofpermanent positive charge; the balance of the composition being monomeror monomers containing a group bearing a centre of permanent positivecharge, and optionally diluent monomer or monomers. Such a compositiontypically comprises up to 95%, preferably to 90%, by weight of diluentcomonomer or comonomers. Where diluent comonomer is present, itpreferably comprises at least 5%, more preferably 10%, by weight of thetotal comonomer composition.

Preferably the molar ratio in the copolymer of comonomer residuesbearing a centre of permanent positive charge to comonomer residuescontaining a reactive group capable of binding the polymer to a surfaceby covalent bonding is from 5:95 to 95:5, more preferably 50:50 to90:10. In addition, the copolymer preferably comprises from 5% to 50%,more preferably 10% to 25%, by mole residues of diluent monomer and/orfrom 0.1% to 20%, more preferably 1% to 10%, by mole residues ofcrosslinkable comononer, provided that where residues of both diluentand crosslinkable comonomer are present, they do not exceed incombination 50%, preferably 35% by mole.

Where the polymer is to bind to a surface by ionic interaction, thenpreferably the molar ratio in the copolymer of comonomer residuesbearing a centre of permanent positive charge to comonomer residuescontaining an ionic group capable of binding the polymer to a surface byionic interactions is from 5:95 to 95:5, more preferably 50:50 to 90:10.In addition, the copolymer preferably comprises from 5% to 50%, morepreferably 10% to 25%, by mole residues of diluent monomer and/or from0.1% to 20%, more preferably 1% to 10%, by mole residues ofcrosslinkable comonomer, provided that where residues of both diluentand crosslinkable comonomer are present, they do not exceed incombination 50%, preferably 35% by mole.

In addition the monomer or comonomer composition may comprise furthercomponents such as a polymerisation initiator, chain transfer agent,acid, base, surfactant, emulsifier or catalyst of conventional type eachin an amount from 0.1% to 5%, typically from 0.2% to 3% and preferablyabout 0.5%, by weight each relative to the total weight of the monomers.

As a further feature the present invention provides a process forbiocompatibilising a surface which comprises coating the surface with apolymer according to the present invention. Various types of surfacesmay be coated depending upon the nature of the groups in the polymercapable of binding it to the surface.

Polymers containing residues of monomers containing alkyl, fluoroalkylor siloxane groups capable of binding the polymer to a surface byphysisorption are particularly suitable for coating hydrophobicsurfaces, e.g. polyethylene, polypropylene and polytetrafluoroethylene(PTFE) surfaces; fluorine containing polymers of the invention beingparticularly suited to coating PTFE surfaces.

Hydrophilic surfaces may be rendered hydrophobic and suitable forcoating with such polymers by known methods (see for example "ChemicalReactions of Polymers" Ed. E. M. Fettes, 1964, Interscience, London).

Treatment with such a polymer is generally carried out by coating thesurface with a solution, dispersion (including a microdispersion) of thepolymer, generally in an alcoholic, aqueous, organic or halogenatedsolvent or a mixture thereof, e.g. methanol, ethanol, dichloromethane orfreon. The treatment is generally carried out at ambient or elevatedtemperature, such as from 5° to 60° C.

In one specific embodiment of the invention, the copolymer is coatedonto the substrate in the form of a microdispersion for example amicroemulsion.

After coating the polymer may be crosslinked if it contains the residuesof crosslinkable comonomer by known method for crosslinking the specificcrosslinkable groups which are present. Crosslinking may, for instance,be introduced thermally, using actinic radiation, using reactive gasesfor example ammonia by changing the pH, using difunctional additives orby using activation chemistries for example by known methods asdescribed in "Methods in Enzymology, volume 135, Immobilised Enzymes andCells, part B", Ed. K. Mosbach, Academic Press Inc, New York, 1987. Thisactivation may be performed on the dry coating, in the cases of thermalradiation or gas treatment. Alternatively for cases where the pH needsto be changed or additives need to be included, activation may beperformed on the coated material in a solution which does not remove thecoating.

Surfaces having functional groups such as hydroxyl, carboxyl or aminogroups are particularly suitable for treatment with polymers accordingto the invention comprising residues of monomer containing a groupcapable of binding the polymer to a surface covalently.

Where necessary the surface of the substrate may be functionalised priorto treatment. For surfaces which do not have functional groups it isnecessary to introduce these groups at the surface before treatment withthe polymer. This can be effected by known etching or derivatisingtechniques, such as plasma discharge, which introduce the appropriatesurface functionality (see for example "Chemical Reactions of Polymers"Ed. E. M. Fettes, 1964, Interscience, London).

In certain cases it is also necessary to activate functional groups atthe surface of the substrate and/or the reactive groups of the polymerof the invention. This may be achieved by known means using a knownactivating agent for example a carbodiimide such as1-ethyl-3-(3-dimethyl-aminopropyl)carbodiimide. Other suitableactivating agents are disclosed in "Methods in Enzymology", supra. Itwill be appreciated that corresponding methods of activation of groupson a polymer may also be used to attach moieties, such as ligands to thepolymer when coated on a substrate.

Treatment with such a polymer is generally carried out by treating thesurface with a solution of the polymer, generally an alcoholic, aqueousalcoholic or aqueous solution. The treatment is generally carried out ata temperature from -5° to 50° C., for from 0.1 to 24 hours and at a pHfrom 2 to 13.

Surfaces having ionic groups such as carboxyl, sulphonate, phosphate,ammonium or phosphonium groups are particularly suitable for treatmentwith polymers according to the invention comprising residues of monomercontaining a group capable of binding the polymer to ionic interaction.

Where necessary the surface of the substrate may be functionalised priorto treatment. For surfaces which do not have ionic groups it isnecessary to introduce these groups at the surface before treatment withthe polymer. This can be effected by known etching or derivatisingtechniques, such as plasma discharge, which introduce the appropriatesurface functionality (see for example "Chemical Reactions of Polymers"Ed. E. M. Fettes, 1964, Interscience, London)

Treatment with such a polymer is generally carried out by treating thesurface with a solution of the polymer, generally an alcoholic, aqueousalcoholic or aqueous solution. Treatment is generally carried out at atemperature from -5° to 50° C., for from 0.1 to 24 hours and at a pHfrom 2 to 13.

Materials may be coated with polymers of the invention by knowntechniques, such as dip-coating, spray-coating, web-coating or spincoating.

Materials having surfaces coated according to the present invention canbe used as a construction material for implants or prostheses for thehuman or animal body, particularly where these implants or prosthesesare to come into direct physical contact with blood and wherebiocompatibility and particularly haemocompatibility are required e.g.in heart valves. They can also be used in the construction of membranesand other devices that are to be brought into contact with blood orother body fluids on an extra-corporeal basis, for example in heart-lungmachines or artificial kidneys.

Additionally the polymers of the invention can be used to coat materialsemployed in down stream processing applications e.g. separationmembranes and process equipment and tubing. In particular the materialsof the invention can be used to modify the surface properties ofbiofiltration membranes in bioreactors and fermentation systems, wherethe membranes come into direct contact with complex biological solutionscontaining e.g. proteins, polysaccharides, fats and even whole cells.The polymers of the invention are particularly useful in reducingmembrane fouling by the components of a process solution.

When the polymers of the present invention are used to coat the surfaceof a material which is then used in the construction coat of finisheddevices, it may be necessary to take precautionary steps to ensure thatthe coated surface is not damaged and the effectiveness of the treatmentreduced before the finished device is produced.

In addition, the polymers of the present invention can be used to coatfinished implants, prostheses, membranes, catheters, contact lenses,intraocular lenses, and other devices which are coated with a polymeraccording to the present invention to impart biocompatibility to thearticle.

The invention thus also provides a finished device comprising a surfacehaving a coating thereon of a polymer of the present invention.

FIG. 1 compares scanning electron micrographs of a polyimide sheettreated and untreated with a copolymer of the invention and thencontacted with blood. FIG. 1. (a) shows a scanning electron micrograph(1200×) of an unsubbed, untreated poly(imide) sheet. FIG. 1. (b) shows ascanning electron micrograph (900×) of a poly(acrylic acid) subbedpoly(imide) sheet treated with poly(2(methacryloyloxyethyl)-2(trimethylammonium)ethylphosphate-co-2-aminomethacrylate) (9:1), in accordance with Example 8.

The present invention will now be further illustrated by the followingExamples:

EXAMPLES

The following assays have been used to evaluate coatings of polymersaccording to the present invention.

Protein adsorption using an enzyme immunoassay

The assay determines adsorption of human fibrinogen at a surface. Thisprotein is representative of protein which is typically adsorbed at asurface. The assay can be readi ly modified to determine the adsorptionof other proteins.

Discs (7 mm in diameter) of untreated material (as controls) andmaterial treated with polymer as described below, were prepared andwashed with phosphate buffered saline (PBS) for at least 10 minutes inthe wells of microplates. The samples were incubated with human plasma(300 μl) for 10 minutes and then washed with PBS three times. Each ofthe test samples and each of the control samples were treated with humanfibrinogen-specific antibody (300μl) for 30 minutes and again washedwith PBS three times. As a control for non-specific binding of antibodyto the samples, each sample was also incubated with non-specificantibody (300 μl) for 3.0 minutes. A conjugate of horseradish peroxidaseand a second antibody specific to the first antibody (300 μl) was addedto both the test samples and the controls and incubated for 30 minutesbefore washing. Each of the test samples and the controls weretransferred to new microplates and a solution of 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) in phosphate-citrate buffer (300μl,0.6 mg/ml) added, the reaction was allowed to proceed for 10 minutes.At this time an aliquot of the mixture (200 μl) was removed and added toa solution of citric acid and sodium azide in distilled water (20 μl,0.21 g/ml and 2 mg/ml respectively). The optical density of thesolutions was measured using a Techgen automated plate reader at 650 nmusing the ABTS solution as blank.

In an alternative procedure, rather than using ABTS, each of the sampleswas transferred to wells of new microplates and a solution ofo-phenylene diamine (OPD) in phosphate-citrate buffer (300 μl, 0.4mg/ml) added, and the reaction was allowed to proceed for 10 minutes. Atthis time an aliquot of the mixture (200 μl) was removed from each welland the optical density of the solutions was measured using a Techgenautomated plate reader at 450 nm using the OPD solution as blank.

Activated Platelet Study

Blood was collected from a healthy adult volunteer using the doublesyringe method where the first 5 ml of blood is discarded. The blood wascollected into tri-sodium citrate (32 g/l) in the proportion of 9volumes to 1 volume citrate in plastic tubes. The samples were kept atroom temperature on a spiral mixer until used.

Discs (7 mm in diameter) of untreated material as controls and materialtreated with polymers as described below were prepared and placed intothe wells of a microplate. The samples were incubated with whole freshcitrated blood (200 μl) on a rotary mixer for 30 minutes before washingin PBS four times. Platelet activation was measured by a proprietaryassay (Lindon, J. N. et al., Blood, 68, 355 (1986)) and British PatentApplication No. 91-25721.2!.

In an alternative procedure half of the test replicates were incubatedwith citrated blood (200 μl) and the remainder were incubated withEDTA-treated blood on a phase shaker for 30 minutes before washing inPBS four times. Platelet activation was measured in a manner similar tothat described above for detection of proteins by enzyme immunoassayusing antibodies against GMP140 to detect the presence of this plateletactivation marker on the surface of biomaterials. In the presence ofEDTA, which extracts calcium from inside platelets, activation isinhibited, so that incubation with EDTA-treated blood acts as anon-specific control for activation, obviating the need for incubationin non-specific antibody.

C-Reactive protein (CRP) binding assay

C reactive protein is a protein which binds specifically to isolatedammonium phosphate esters groups e.g. phosphoryl choline groups whichare attached to a surface.

Discs (7 mm in diameter) of untreated material and material treated withpolymer as described below, were prepared and washed with HEPES-bufferedsaline (HBS) for a least 10 minutes in the wells of microplates. Thesamples were incubated in quadruplet for 45 minutes in a proteinsolution consisting of bovine serum albumin (BSA) (40 mg/ml) and CRP(0.012 mg/ml) in HBS and containing calcium chloride (1 mM). Inparallel, identical samples (both coated and uncoated) were incubatedeither in BSA/Ca²⁺ solution in the absence of CRP, in BSA/CRP/Ca²⁺solution in the presence of soluble phosphoryl choline (1.5 mg/ml) or inBSA/CRP solution containing EDTA (20 mM) rather than calcium chloride.

After incubation, all the samples were washed in phosphate bufferedsaline (PBS) three times and then incubated for 1 hour in ³⁰⁰ μl of a1:100 dilution of commercially available anti-CRP antibody conjugatedwith horseradish peroxidase. The samples were washed three times in PBSas before and transferred to new microplates. A solution of o-phenylenediamine (OPD, 0.4 mg/ml) in phosphate-citrate buffer was added and thereaction allowed to proceed for ten minutes. At this time an aliquot ofthe mixture (200 μl) in each of the wells was transferred to a new well,and the optical density of the solutions measured using a Techgenautomated plate reader at 450 nm using the OPD solution as a blank.

A positive control containing isolated phosphoryl choline groups may beprovided using beaded agarose immobilised with p-aminophenylphosphorylcholine. The specificity of CRP binding may be demonstrated byinhibition by phosphoryl choline and dependance upon the presence ofcalcium.

EXAMPLE 1 Preparation ofpoly(2(methacryloyloxvethyl)-2'(trimethylammonium)ethyl phosphate innersalt -co-n-dodecyl methacrylate (1:2)

2 (Methacryloyloxyethyl) -2'(trimethylammonium) ethyl phosphate innersalt (5.0 g, 0.0170 mole) and n-dodecylmethacrylate (8.55 g, 0.0340mole) were dissolved in methanol/THF (140 ml, 5:9). The solution wasstirred (250 rpm) at 23° C. under a stream of nitrogen (50 ml/min) for30 minutes. 2,2'-Azo-bis(2-methylpropionitrile) (0.17 g,1.02 mmole) wasadded and the flow of nitrogen was reduced to 10 ml/min, the temperaturewas raised to 60° C. This temperature and nitrogen flow rate weremaintained for 16 hours.

The mixture was allowed to cool and vacuum filtered. The filtrate wascollected and the polymer precipitated by dropwise addition to acetone(1.21).

The polymer was isolated by filtration under vacuum under a nitrogenatmosphere and finally dried under reduced pressure overnight at roomtemperature. The resulting polymer (9.5 g,70%) was a fine white powder.

In an alternative procedure,2(methacryloyloxyethyl)-2'(trimethylammonium)ethyl phosphate inner salt(12.06 g, 0.0409 mole) and n-dodecyl methacrylate (20.52 g, 0.0808 mole)were dissolved in propan-2-ol (215 ml) and ethyl acetate (85 ml). Thesolution was stirred (250 rpm) at 23° C. under a stream of nitrogen (50ml/min) for 30 minutes, 2,2'-azo-bis(2-methylpropionitrile) (0.0645 g,0.39 mmole) was added and the flow of nitrogen was reduced to 10 ml/min,the reaction temperature was raised to 60° C. This temperature andnitrogen flow rate were maintained for 40 hours.

The mixture was allowed to cool and vacuum filtered. The filtrate wasevaporated to dryness using a rotary evaporator and dissolved indichloromethane (120 ml) and methanol (10 ml). The polymer was isolatedfrom this mixture by precipitation in acetone (2500 ml), vacuumfiltration and drying. The polymer was redissolved in dichloromethane(100 ml) and methanol (30 ml) and isolated as described above.

The resulting polymer, obtained in 70-80% yield was a white powder.

NMR(200 MHz, d, ppm, CD₃ OD/CDCl₃) 4.2-4.4 (b), 3.8-4.2 (b), 3.6-3.8(b), 3.3 (s), 1.8-2.2 (b), 1.5-1.8 (b), 1.2-1.5 (s), 0.8-1.0 (s)

IR(cm⁻¹, KBr disc) 3430, 2929, 2854, 1732, 1469, 1246, 1156, 1089, 968,788.

    ______________________________________                                        Elemental Analysis                                                            ______________________________________                                        theory    C 64.5, H 9.9,      N 1.8,                                                                              P 3.9                                     actual    C 59.0, H 10.0,     N 1.8,                                                                              P 3.9                                     ______________________________________                                    

The polymer had a relative viscosity in ethanol: chloroform (50:50) at25° C. of 1.13±0.02 (when prepared using methanol: THF as solvent) and1.26±0.02 (when prepared using propan-2-01: ethylacetate as solvent).

EXAMPLE 2 The coating of poly(ethylene) ribbon withpoly(2(methacryloyloxyethyl)-2'(trimethylammonium)ethyl phosphate innersalt -co- n-dodecyl methacrylate (1:2)

Poly(ethylene) ribbon was washed with ethanol and allowed to dry in theair. The poly(2(methacryloyloxyethyl)-2'(trimethylammonium)ethylphosphate inner salt -co- n-dodecyl methacrylate) (1:2) (5Omg) wasdissolved in ethanol/chloroform (5 ml, 40:1) and the poly(ethylene)coated by a one stage mechanical dip-coating procedure drawing theribbon through the solution slowly. The coated ribbon was allowed to dryin a dust free atmosphere at room temperature.

The treated poly(ethylene) showed a 65% reduction in protein adsorptionas compared to the untreated material and a 83% reduction in plateletactivation (determined using the assay of Lindon et al) as compared tothe untreated material.

In the C-reactive protein binding assay, no binding of CRP was observedto the treated poly(ethylene). In contrast, CRP binding was observed fora positive control. The specificity of this CRP binding was demonstratedby the fact that it was inhibited by phosphoryl choline and dependenceupon the presence of calcium.

According to an alternative procedure, polyethylene ribbon was washed inpropan-2-ol and coated with the copolymer dissolved in propan-2-ol (1 gin 100 ml) at 40° C. using an otherwise analogous manner.

EXAMPLE 3

In an analogous manner to that described in Example 2 steel and PVCsubstrates were coated with poly(2 (methacryloyloxyethyl)-2'(trimethylammonium) ethyl phosphate inner salt -co-n-dodecylmethacrylate (1:2).

The treated steel samples showed a reduction in protein adsorption ofover 80% compared to untreated samples and the treated PVC samplesshowed a reduction in protein adsorption of over 70% compared tountreated samples as measured by the enzyme immunoassay described above.In a further determination a sample of stainless steel coated with thepolymer showed a reduction, compared to untreated material, in proteinadsorption of 84% as determined by the enzyme immunoassay technique anda reduction of 95% in platelet activation as determined by the plateletactiviation assay described above using anti-GMP140. A further sample ofPVC coated with the polymer showed a reduction of 87% in proteinadsorption and a reduction of 100% in platelet activation, compared tountreated material, using the same assay techniques.

EXAMPLE 4 Preparation ofpoly(2(methacryloyloxyethyl)-2'(trimethylammonium)ethyl phosphate innersalt-co-n-dodecyl methacrylate (1:4)

2 (Methacryloyloxyethyl) -2'(trimethylammonium) ethyl phosphate innersalt (10.00 g, 0.0339 mole) and n-dodecyl methacrylate (35.56 g, 0.1400mole) were dissolved in propan-2-ol (200 ml) and ethyl acetate (200 ml).The solution was stirred (250 rpm) at 23° C. under a stream of nitrogen(50 ml/min) for 30 minutes. 2,2'-azo-bis-(2-methylpropionitrile) (0.0886g, 0.54 mmole) was added and the flow of nitrogen was reduced to 10ml/min, the reaction temperature was raised to 60° C. This temperatureand nitrogen flow rate were maintained for 40 hours.

The mixture was allowed to cool and vacuum filtered. The filtrate wasevaporated to dryness using a rotary evaporator and dissolved indichloromethane (130 ml). The polymer was isolated from this mixture byprecipitation in acetone (2500 ml), vacuum filtration and drying. Thepolymer was redissolved in dichloromethane (120 ml) and methanol (10 ml)isolated as before.

The resulting polymer, obtained in 70-80% yield was a white solid.

NMR(200 MHz, d, ppm, CD₃ OD/CDCl₃) 4.2-4.4 (b), 3.8-4.2 (b), 3.6-3.8(b), 3.3 (s), 1.8-2.2 (b), 1.5-1.8 (b), 1.2-1.5 (s), 0.8-1.0 (s)

IR(cm⁻¹, KBr disc) 3430, 2929, 2854, 1732, 1469, 1246, 1156, 1089, 968,788.

    ______________________________________                                        Elemental Anaylsis:                                                           ______________________________________                                        theory    C 68.9, H 10.5,     N 1.1,                                                                              P 2.4                                     actual    C 65.5, H 10.8,     N 1.1,                                                                              P 2.4                                     ______________________________________                                    

The polymer had a relative viscosity in ethanol: chloroform (50.50) at25° C. of 1.26±0.02.

Samples of polyethylene, steel and PVC were coated using the methodsdescribed in Examples 2 and 3. Using the enzyme immunoassay for proteinadsorption, a greater than 80% reduction in protein adsorption on steeland greater than 70% reduction in protein adsorption on PVC wereobtained.

In a further determination, a sample of stainless steel coated with thepolymer showed a reduction of 80% in protein adsorption (determined bythe enzyme immunoassay described above) and a reduction of 95% inplatelet activation (determined by the platelet activation assaydescribed above using anti-GMP 140), compound to untreated material. Asample of PVC coated with the polymer showed a reduction of 70% inprotein adsorption and 100% in platelet activation compound to untreatedmaterial using the same assay techniques.

EXAMPLE 5 Preparation ofpoly(2(methacryloyloxyethyl)-2'(trimethylammonium)ethyl phosphate innersalt-co-1H. 1H, 2H,2H,heptadecafluorodecyl methacrylate (2:1)

2(methacryloyloxyethyl)-2'(trimethylammonium)ethyl phosphate inner salt(1.0 g, 0.0034 mole) and 1H, 1H, 2H, 2H-heptadecafluorodecylmethacrylate (0.90 g, 0.0017 mole) were dissolved in methanol (10 ml)and tetrahydrofuran (10 ml). The solution was stirred (250 rpm) at 23°C. under a stream of nitrogen (50 ml/min) for 30 minutes.2,2'-azo-bis(2-methylpropionitrile) (0.0167 g, 0.lommole) was added andthe flow of nitrogen was reduced to 10 ml/min, the reaction temperaturewas raised to 60° C. This temperature and nitrogen flow rate weremaintained for 16 hours.

The mixture was allowed to cool and vacuum filtered. The filtrate wasevaporated to dryness using a rotary evaporator and dissolved indichloromethane (10 ml) and methanol (10 ml). The polymer was isolatedfrom this mixture by precipitation in acetone (500 ml), vacuumfiltration and drying. The polymer was redissolved in dichloromethane(10 ml) and methanol (10 ml) and isolated as before. The resultingpolymer, obtained in 70-80% yield was a white powder.

NMR(200 MHz, d, ppm, CD₃ OD/CDCl₃) 4.2-4.4 (b), 3.8-4.2 (b), 3.6-3.8(b), 3.3 (s), 2.4-2.7(b), 2.2-1.7(b), 1.2-1.0(b), 0.8-1.0 (b)

The polymer was used to coat a polyvinylidene fluoride microfiltrationmembrane. The resulting coated membrane showed very little flux declineduring processing with bovine serum albumin (BSA) indicating very littleprotein fouling. The flux change for the treated membrance was from 6000to 5000 l/m² /hr compared to the flux change for the untreated membranewhich was from 5000 to 500 l/m² /hr. Both measurements were taken over atwo hour period.

EXAMPLE 6 Preparation ofpoly(2(methacrylovloxyethyl)-2'trimethylammonium) ethyl phosphate innersalt-co-n-hexadecyl methacrylate (1:2)

2 (methacryloyloxyethyl) -2'(trimethylammonium) ethyl phosphate innersalt (2.00 g, 6.78 mmole) and n-hexadecyl methacrylate (4.21 g, 0.0136mole) were dissolved in propan-2-ol (35.5 ml) and ethyl acetate (14.5ml). The solution was stirred (250 rpm) at 23° C. under a stream ofnitrogen (50 ml/min) for 30 minutes. 2,2'-azo-bis(2-methylpropionitrile)(0.0168 g, 0.10 mmole) was added and the flow of nitrogen was reduced to10 ml/min, the reaction temperature was raised to 60° C. Thistemperature and nitrogen flow rate were maintained for 40 house.

The mixture was allowed to cool and vacuum filtered. The filtrate wasevaporated to dryness using a rotary evaporator and dissolved indichloromethane (10 ml) and methanol (10 ml). The polymer was isolatedfrom this mixture by precipitation in acetone (700 ml), vacuumfiltration and drying. The polymer was redissolved in dichloromethane(10 ml) and methanol (10 ml) isolated as described above. The resultingpolymer, obtained in 40-60% yield was a white solid.

NMR(200 MHz, d, ppm, CD₃ OD/CDCl₃) 4.2-4.4 (b), 3.8-4.2 (b), 3.6-3.8(b), 3.3 (s), 1.8-2.2 (b), 1.5-1.8 (b), 1.2-1.5 (s), 0.8-1.0 (s).

IR(cm⁻¹, KBr disc) 3430, 2929, 2854, 1732, 1469, 1246, 1156, 1089, 968,788.

EXAMPLE 7 Preparation ofpoly(2(methyacryloyloxyethyl)-2(trimethyl-ammonium)ethyl phosphate innersalt -co- 2-aminoethyl-methacrylate) (9:1)

2(Methacryloyloxyethyl)-2(trimethylammonium)ethyl phosphate inner salt(9.96 g, 0.0335 mole) was dissolved in methanol (115 ml). Water (10 ml)was added followed by the addition of 2-aminoethylmethacrylate (0.5571g, 0.0034 mole). The solution was stirred (250 rpm) at 22° C. under astream of nitrogen (70 ml/min) for 30 minutes.2,2'Azo-bis(2-methylpropionitrile) 0.12 g, 0.73 mmole) was added and theflow of nitrogen was reduced to 9 ml/min, the temperature was raised to60° C. The temperature and nitrogen flow rate were maintained for 16hours.

The mixture was allowed to cool and transferred to centrifuge tubes. Thesamples were centrifuged for 30 minutes at 4000 rpm. The samples werecombined and the polymer precipitated by dropwise addition to acetone(800 ml). The acetone was decanted from the polymer and the polymerwashed with acetone (200 ml). The polymer was isolated by vacuumfiltration under a nitrogen atmosphere and finally dried in vacuoovernight at room temperature.

IR (cm⁻¹ ;KBr disc) 3435, 2929, 2096, 1732, 1628, 1245, 1166, 1089, 970.

EXAMPLE 8 Treatment of poly(acrylic acid) subbed poly(imide) sheets withpoly(2(methacryloyloxyethyl)-2(trimethylammonium) ethyl phosphate innersalt -co- 2-aminoethylmethacrylate) (9:1).

Poly(imide) samples were placed in the plasma chamber of a plasma barreletcher and evacuated with a pump down to a pressure of 0.001 mbar.Oxygen was then allowed to flow into the reactor. The plasma was startedwith 90 W forward power and nearly OW backward. The pressure wasapproximately 0.7 mbar. The plasma was turned on for 5 minutes, then theradio frequency generator (13.56 MHz) was switched off at the same timeas the flow of oxygen stopped. The pressure was allowed to drop and thevalve of the flask with acrylic acid was opened to let the monomer flowinto the chamber (100% acrylic acid). The vacuum was decreased to 0.3mbar. The high frequency generator was then started with 30W forwardpower and OW backward power and the polymerisation carried out for 20minutes. After switching off the high frequency generator and closingthe valve to the acrylic acid, the chamber was evaporated again foranother 5 minutes to remove all of the excess monomer.

The poly(acrylic acid) subbed poly(imide) was cut into 4×1.5cm² piecesand washed with distilled water. The squares were then added to a 1.25%solution (6.3 ml) of poly(2(methacryloyloxyethyl)-2(trimethylammonium)ethyl phosphate inner salt -co- 2-aminoethylmethacrylate (9:1).1-Ethyl-3(3-dimethylaminopropyl)carbodiimide (20 g) was then dissolvedin the solution and the pH then adjusted to 5.0 using hydrochloric acid(0.5M). After 1 hour the samples were removed, washed with distilledwater and allowed to dry.

Visualisation of Platelet Activation on a Surface

Blood was collected from a healthy adult volunteer using the doublesyringe method where the first 5 ml of blood is discarded. The blood wascollected into tri-sodium citrate (32 g/1) in the proportion of 9volumes of blood to 1 volume citrate in plastic tubes. The samples werekept at room temperature on a spiral mixer until used.

1 cm² samples of poly(2(methacryloyloxyethyl)-2-(trimethylammonium)ethylphosphate inner salt -co- 2-aminoethylmethacrylate) (9:1) coatedpoly(imide) as prepared above and of uncoated poly(imide) as acomparison were placed into 1 ml of the fresh citrated blood andincubated for 30 minutes on a spiral mixer at room temperature. Thesamples were then washed in phosphate buffered saline (PBS,pH7.4) priorto fixing in an aliquot of the following solution for 30 minutes.

2 ml 25% w/v glutaraldehyde

83 ml 0.15M PBS (pH7.4)

15 ml Saturated picric acid.

Picric acid increases the preservation of lipid-associated protein. Thesamples were again washed in PBS and then dehydrated using 70% and 100%methanol followed by 100% acetone prior to drying in air. Finallysamples were sputter-coated with a platinum target (20 mAmps for 6×30seconds) and observed at appropriate magnifications using a scanningelectron microscope.

No platelet activation was seen on the coated poly(imide) sampleswhereas gross adhesion activation and aggregation were seen on theuncoated sample (see FIG. 1). The presence of the polymer on the surfacewas confirmed by the use of X-ray photoelectron spectroscopy (XPS). Itcan thus be seen that treatment of polyamide by first coating with asubbing layer of acrylic acid to render the surface reactive, and thencoating with a copolymer according to the present inventionsubstantially removed the haemostatic reaction to the polyamide.

EXAMPLE 9 Preparation ofpoly(2(methacryloyloxyethyl)-2'(trimethylammonium) ethyl phosphate innersalt-co-3-chloro-2-hydroxypropyl methacrylate (1:1)

2(methacryloyloxyethyl)-2'(trimethylammonium)ethyl phosphate inner salt(7.46 g, 25.3 mmole), 3-chloro-2-hydroxypropyl methacrylate (4.51 g,25.3 mmole) and p-toluene sulphonic acid monohydrate (0.1048 g, 0.55mmole) were dissolved in methanol (101 ml). The solution was stirred(250 rpm) at 23° C. under a stream of nitrogen (50 ml/min) for 30minutes. 2,2'-azo-bis(2-methylpropionitrile) (0.0843 g, 0.51 mmole) wasadded and the flow of nitrogen was reduced to 10 ml/min, the reactiontemperature was raised to 60° C. This temperature and nitrogen flow ratewere maintained for 16 hours.

The polymer was isolated from this mixture by precipitation in acetone(1500 ml), vacuum filtration and drying. The polymer was redissolved inmethanol (40 ml) and isolated as before using acetone (1000 ml).

The resulting polymer, obtained in 62% yield was a white solid.

NMR(200 MHz, d, ppm, CD₃ OD/CDCl₃) 4.2-4.4 (b), 4.3-4.0 (b), 3.6-3.8(b), 3.3 (s), 1.6-2.4(b), 1.0-1.5(b), 0.7-1.0(b).

IR(cm⁻¹, KBr disc) 3416, 2959, 1727, 1655, 1490, 1247, 1165, 1088, 968,792, 748.

EXAMPLE 10 Preparation ofpoly(2(methacryloyloxyethyl)-2'(trimethylammonium)ethyl phosphate innersalt -co- 7 dodecynmethacrylate (1:2)

The polymer was prepared by a method analogous to that described inExamples 4 and 6 using2(methacryloyloxyethyl)-2'(trimethylammonium)ethyl phosphate inner salt(8.41 g, 0.0285 mole) and n-dodecynmethacrylate (14.31 g, 0.0572 mole)dissolved in propan-2-ol (160 ml) and ethyl acetate (60 ml).

The resulting polymer, obtained in 35% yield was a white powder.

NMR(100 MHz,d,ppm,CD₃OD/CDCl₃)4.2-4.4(b),3.8-4.2(b),3.6-3.8(b),3.3(s),2.25(s),1.8-2.2(b),1.5-1.8(b),1.2-1.5(s),0.8-1.0(s)

IR(cm³¹ 1,KBr disc) 3430, 2929, 2854, 1732, 1469, 1246, 1156, 1089, 968,788.

    ______________________________________                                        Elemental Analysis                                                            ______________________________________                                        theory      C 65.1  H 9.0      N 1.8                                                                              P 3.9                                     actual      C 54.9  H 8.5      N 1.9                                                                              P 4.4                                     ______________________________________                                    

Relative Viscosity (chloroform/ethanol 50:50, 30° C.) 1.18.

The polymer may be crosslinked by gamma-irradiation or exposure to UVlight which renders the polymer insoluble in dichloromethene/methanol.

A sample of stainless steel treated with the polymer showed a reductionin protein adsorption of 68% (determined by the enzyme immunoassaydescribed above) and a reduction in platelet activation of 100%(determined by the platelet activation assay described above, using antiGMP 140) compared to untreated material. A sample of PVC coated with thepolymer showed a reduction in protein adsorption of 60% compared tountreated material as determined by the same assay technique.

EXAMPLE 11 Preparation ofpoly(2(acryloyloxyethyl)-2'(trimethylammonium)ethyl phosphate inner salt-co- n-dodecyl methacrylate)(1:2)

The polymer was prepared by a method analogous to that described inExamples 4 and 6 using 2(acryloyloxyethyl)-2'(trimethylammonium)ethylphosphate inner salt (3.0 g, 0.0107 mole) and n-dodecyl methacrylate(5.42 g, 0.0214 mole) dissolved in propan-2-ol (53 ml) and ethyl acetate(22 ml).

The resulting polymer, obtained in 58% yield was a white solid.

NMR(100 MHz,d,ppm,CD₃ OD/CDCl₃)4.2-4.4(b),3.8-4.2(b),3.6-3.8(b),3.3(s),1.8-2.2(b),1.5-1.8(b),1.2-1.5(s),0.8-1.0(s)

IR(CM⁻¹,KBr disc) 3430, 2929, 2854, 1732, 1469, 1246, 1156, 1089, 968,788.

    ______________________________________                                        Elemental Analysis                                                            ______________________________________                                        theory      C 64.9  H 8.7      N 1.8                                                                              P 4.0                                     actual      C 57.8  H 9.8      N 2.1                                                                              P 4.9                                     ______________________________________                                    

A sample of stainless steel treated with the polymer showed a reductionin protein adsorption of 53% (determined by the enzyme immunoassaydescribed above) and a reduction in platelet activation of 100%(determined by the platelet activation assay described above, usinganti-GMP140) compared to untreated material. A sample of PVC treatedwith the polymer showed a reduction in protein adsorption of 68% and areduction in platelet activation of 100% compared to untreated materialdetermined by the same assay techniques.

EXAMPLE 12 Preparation ofpoly(2(methacryloyloxyethyl)-2'(trimethylammonium)ethyl phosphate innersalt -co- n-hexyl methacrylate ((1:2)

The polymer was prepared by a method analogous to that described inExamples 4 and 6 using2(methacryloyloxyethyl)-2'(trimethylammonium)ethyl phosphate innersalt(2.0 g, 0.0068 mole) and n-hexyl methacrylate (2.31 g, 0.0136 mole)dissolved in propan-2-ol (35.5 ml) and ethyl acetate (14.5 ml).

The resulting polymer, obtained in 34% yield was a white solid.

NMR(100 MHz,d,ppm,CD₃OD/CDCl₃)4.2-4.4(b),3.8-4.2(b),3.6-3.8(b),3.3(s),1.8-2.2(b),1.5-1.8(b),1.2-1.5(s),0.8-1.0(s)

IR(cm⁻¹,KBr disc) 3430, 2929, 2854, 1732, 1469, 1246, 1156, 1089, 968,788.

    ______________________________________                                        Elemental Analysis                                                            ______________________________________                                        theory      C 58.8  H 8.8      N 2.2                                                                              P 4.9                                     actual      C 47.3  H 7.9      N 2.6                                                                              P 5.8                                     ______________________________________                                    

EXAMPLE 13 Preparation ofpoly(2(methacryloyloxvethyl)-2'(trimethylammonium)ethyl phosphate innersalt -co- n-octadecyl methacrylate) (1:2)

The polymer was prepared by a method analogous to that described inExample 5 using 2(methacryloyloxyethyl)-2'(trimethylammonium)ethylphosphate inner salt(3.0 g,0.0102 mole) and n-octadecyl methacrylate(6.90 g,0.0204 mole) dissolved in methanol (30 ml) and THF (70 ml). Thereaction mixture rate was maintained for 40 hours at 60° C. The polymerwas isolated from this mixture by precipitation in acetone (1200 ml),vacuum filtration and drying. The resulting polymer, obtained in 55%yield was a white solid.

NMR(100 MHz,d,ppm,CD₃ OD/CDCl₃)4.2-4.4 (b),3.8-4.2 (b),3.6-3.8(b),3.3(s),1.8-2.2(b),1.5-1.8(b),1.2-1.5(s),0.8-1.0(s)

IR(cm⁻¹,KBr disc) 3430, 2929, 2854, 1732, 1469, 1246, 1156, 1089, 968,788.

EXAMPLE 14 Preparation of poly(2(methacryloyloxyethyl)-2'(trimethylammonium)ethyl phospate inne salt-co- n-dodecyl methacrylate -co- 2 hydroxvethvlmethacrylate) (17:75:8)

The polymer was prepared by a method analogous to Examples 4 and 6,using 2(methacryloyloxyethyl)-2'(trimethylammonium)ethyl phosphate innersalt (2.0 g,0.0068 mole), n-dodecyl methacrylate (7.65 g, 0.0301 mole)and 2-hydroxyethyl methacrylate (0.42 g, 0.0032 mole) dissolved inpropan-2-ol(70 ml) and ethyl acetate (30 ml).

The resulting polymer, obtained in 53% yield was a white solid.

NMR(100 MHz,d,ppm,CD₃ OD/CDCl₃)4.2-4.4(b)3.8-4.2(b),3.6-3.8(b),3.3(s),1.8-2.2(b),1.5-1.8(b),1.2-1.5(s),0.8-1.0(s).

IR(cm⁻¹,KBr disc) 3435, 2925, 2860, 1729, 1468, 1243, 1152, 1089, 969,791.

A coating solution ofpoly(2(methacryloyloxyethyl)-2'(trimethylammonium)ethyl phospate innersalt -co- n-dodecyl methacrylate -co- 2-hydroxyethylmetacrylate) (0.5097g) in propan-2-ol (50 ml) was prepared. Aluminium sheet was washed withpropan-2-ol, hexane and water and dried, the coating solution (0.5 ml)was applied to pieces of the aluminium sheet (7.5 cm²) by a spin coatingtechnique using a spin speed of 1200 rpm.

EXAMPLE 15 Preparation ofpoly(2(methacryloyloxyethyl)-2'(trimethylammonium)ethyl phosphate innersalt -co- Methacrylic acid (7:3)

The polymer was prepared by a method analogous to that of Examples 4 and6 using 2(methacryloyloxyethyl)-2'(trimethylammonium)ethyl phosphateinner salt (4.44 g,0.0149 mole), and methacrylic acid (0.54 g,0.0063mole) dissolved in propan-2-ol (25 ml) and water (25 ml). The polymerwas isolated by precipitation in acetone (500 ml), redissolved inmethanol (50 ml) and isolated by precipitation in diethylether (500 ml).

The resulting polymer, obtained in 30% yield was a white solid.

NMR(100 MHz,d,ppm,CD₃OD/CDCl₃)4.2-4.4(b),3.8-4.2(b),3.6-3.8(b),3.3(s),1.8-2.2(b),1.5-1.8(b),₁.2-1.5(s),0.8-1.0(s)

IR(cm⁻¹,KBr disc) 3430, 2929, 2854, 1732, 1469, 1246, 1156, 1089, 968,788.

This polymer was used to treat cellulose film which had been treatedwith 2-aminoethyl methacrylate as follows:

A section of cellulose dialysis membrane (4×6cm) was taken, and placedinto a solution of 2-aminopropylmethacrylate (3.34 g) and ceric ammoniumnitrate (0.05 g) in distilled water (20 ml). The solution wasdeoxygenated with N₂ for 10 minutes, then the vessel was sealed, andleft at room temperature for 2 hours. The cellulose sample was thenremoved from the solution, then washed extensively in distilled waterfor 24 hours.

The presence of amine hydrochloride moieties on the grafted sample wasdemonstrated by the differential uptake of anionic and cationic dyes(Trypton blue and methylene blue respectively).

Strips of the functionalised cellulose (0.5cm×2cm) were placed in a 10%w/w solution of the polymer in water. The samples were left to stand atroom temperature for 1 hour, then washed extensively in distilled water(200 ml) for 2 hours.

Following the aqueous wash, the treated cellulose was placed into asolution of acid molybdate spray reagent and left to stand for 1 hour,then removed and washed with distilled water. The presence of phosphategroups on the sample was demonstrated by the development of a bluecolour.

EXAMPLE 16 Preparation ofpoly(2(methacryloyloxvethyl)-2'(trimethylammonium)ethyl phosphate innersalt -co- (2-methacryoyloxyethyl trimethylammonium chloride (7:3)

2(Methacryloyloxyethyl)-2'(trimethylammonium)ethyl phosphate inner salt(4.45 g,0.0151 mole), 2-methacryoyloxyethyl trimethylammoniumchloride(1.96 g of a 75% aqueous solution, 0.0071 mole) were dissolvedin ethanol (50 ml). The solution was stirred (250 rpm) at 23° C. under astream of nitrogen (50 ml/min) for 30 minutes.2,2'-Azo-bis(2-methylpropionitrile) (0.02 g,0.122 mole) was added andthe flow of nitrogen was reduced to 10 ml/min, the reation temperatureas raised to 60° C. This temperature and nitrogen flow rate eremaintained for 40 hours.

The mixture was allowed to cool and filtered under vacuum. The polymerwas isolated from this mixture by precipitation in diethylether (500ml), vacuum filtration and drying.

The resulting polymer, obtained in 68% yield was a white solid.

NMR(100 MHz,d,ppm,CD₃ OD/CDCl₃) 4.2-4.4(b) ,3.8-4.2(b) ,3.6-3.8(b),3.3(s),1.8-2.2(b),1.5-1.8(b),1.2-1.5(s),0.8-1.0(s)

IR(cm⁻¹,KBr disc) 3430, 2929, 2854, 1732, 1469, 1246, 1156, 1089, 968,788.

The polymer was used to treat cellulose film which had been treated with3-sulfopropyl methacrylate potassium salt using the method described inExample 15 but using 3-sulfopropyl methacrylate potassium salt (4.92 g)rather than 2-aminopropyl methacrylate.

The presence of sulphate moieties on the grafted sample was demonstratedby the differntial uptake of anionic and cationic dyes (Trypton blue andmethylene blue respctively).

Strips of the functionalised cellulose (0.5cm×2cm) were treated with alot w/w solution of the polymer in water in an analogous manner to thatdescribed in Example 15 and the presence of phosphate groups wasdemonstrated in the same way.

EXAMPLE 17 Preparation ofpoly(2(methacryloyloxyethyl)-2'(trimethylammonium)ethyl phosphate innersalt -co- n-dodecyl methacrylate (14:86)

The polymer was prepared by a method analogous to that described inExample 1 using a comonomer mixture consisting of 2(methacryloyloxyethyl) -2'(trimethylammonium) ethyl phosphate inner saltand n-dodecyl methacrylate in a molar ratio of 14:86 usingpropan-2-ol/ethylacetate solvent.

A PVC substrate was coated with the polymer using a method analogous tothat described in Example 3.

Comparative Example

The fibrinogen adsorption and C-reactive protein binding to PVCsubstrates coated with polymers of the invention in accordance withExamples 3 and 17 was compared with that for copolymers of2(methacryloyloxyethyl)-2'(trimethylammonium)ethyl phosphate, inner saltand butyl methacrylate in a molar ratio of 1:2 (Comparison A) and 14:86(Comparison B). The comparison copolymers were prepared by a methodanalogous to that described in Example 1 and coated onto the PVCsubstrate using a method analogous to that described in Example 3. Allthe copolymers were prepared using the procedure described under Example1 using a propan-2-ol/ethylacetate solvent. The results are shown in thefollowing Table:

    ______________________________________                                                   Example     Comparison                                                        3      17       A        B                                         ______________________________________                                        Fibrinogen Adsorption                                                                      87       60       82     72                                      C-reative Protein                                                                          0.094    0.043    0.101  0.139                                   Protein Index (×10.sup.3)                                                            1.1      0.7      1.9    1.9                                     ______________________________________                                    

The results were obtained using the assay techniques described aboveafter incubation in PBS for 24 hours. The fibrinogen adsorption resultsare expressed as a percentage reduction in optical density relative tountreated Polyvinylidene chloride. C-reactive protein results areexpressed as absorbance due to C-reactive protein; a positive controlshowed CRP binding. Protein index is the ratio of C-reactive proteinbinding to fibrinogen adsorption.

These results show that in order to obtain a good reduction in proteinadsorption using copolymers containing butylmethacrylate a highC-reactive protein binding must be accepted. In contrast, using longerchain alkyl monomers good reduction in protein adsorption and lowC-reactive protein binding are obtained as well as good adhesion to thesubstrate and low swelling in aqueous environments.

Copolymers containing comonomers comprising short chain alkyl groups ofup to 4 carbon atoms as potential physisorbable groups such as butylmethacrylate, in smaller molar proportions, exhibit poor adhesion tohydrophobic substrates and are subject to high swelling in aqueousenvironments which renders them unsuitable for use in coating surfaces.

EXAMPLE 18

Polymers from examples 1 and 4 were coated onto PVC tubing and theirperformance assessed in an extracorporeal system using a left heartbypass procedure in a calf model. Blood was pumped around the systemcontinuously at physiological temperature in the absence ofanticoagulant at a rate of 3.5 litre per minute. Parameters associatedwith the condition of circulating blood were measured throughout theexperiments.

Virtually all the parameters tested gave results which showed that thepresence of the coated circuit had little or no effect on the blood andthe physiological function of the animals (typically three identicalexperiments were run on consecutive days and were very reproducible fromanimal to animal).

In comparison with the above an uncoated circuit cannot be successfullyrun for a continuous 6 hour period without the use of anticoagulant.Also blood parameters are very adversely affected in a short period oftime.

Results of protein adsorption tests and macroscopic observation ofcircuit components indicate that both coatings perform at least as wellas heparinised tubing and that, in areas of the circuit where highturbulence in the flow of the blood occurs, fewer clots were found.

Reference Example 1 Preparation of2(methacryloyloxyethyl)-2'(trimethylammonium ethyl phosphate inner salt

The preparation is illustrated by the reaction scheme A which follows.

a) 2-Chloro-1,3-dioxaphospholane (1)

In a flask fitted with a pressure equalising dropping funnel, refluxcondenser (fitted with a CaCl₂ guard tube) and magnetic stirrer, wasplaced a solution of phosphorus trichloride (220 ml; 346.3 g; 2.52 mol)in dichloromethane (500 ml). Ethylene glycol (139 ml; 154.7 g, 2.49 mol)was then added dropwise via the dropping funnel at such a rate that theevolution of HCl did not become too excessive. On the addition of theethylene glycol, the condenser was arranged for distillation, and thedichloromethane removed at atmospheric pressure. When the distillatetemperature reached 60° C. the flask was arranged for vacuumdistillation using a water pump, Distillation then gave2-chloro-1,3-dioxaphospholane (158 ml; 224.5 g; 71.3%) as a colourlessmobile liquid (which fumes in moist air) b.pt. 36°-40° C./21 mm Hg. cf45.5°-47° C./20 mm Hg, Lucas et al, J. Am. Chem. Soc., 72, 5491,(1950)!.

IR (cm-⁻¹, thin film) 2980, 2905, 1470, 1210, 1005, 930, 813, 770.

b) 2-Chloro-2-oxo-1,3,2-dioxaphospholane (2)

In a flask fitted with a magnetic stirrer, reflux condenser (fitted witha CaCl₂ guard tube) and sintered glass gas inlet tube, was placed asolution of 2-chloro-1,3-2-dioxaphospholane (100.8 g; 0.797 mol) in drybenzene (200 ml). The solution was stirred and a steady stream of oxygenwas bubbled through the solution. The reaction was mildly exothermic,and temperature control was achieved by allowing the solvent to reflux.The oxygen was passed through the reaction mixture for 6 hours. Thesolvent was removed by rotary evaporation, and the colourless mobileresidue distilled to give 2-chloro-2-oxo-1,3,2-dioxaphospholane (2)(87.41 g; 77%) as a colourless mobile liquid -b.pt 95°-97° C./0.2 mbar(c.f. 102.5°-105° C./1 mbar (Edmundson, Chem. Ind. (London)), 1828(1962); 79° C./0.4 mbar Umeda et al., Makromol. Chem. Rapid Commun., 3,457, (1982)!.

IR(cm⁻¹, thin film) 2990, 2910, 1475, 1370, 1310, 1220, 1030, 930, 865,830.

c) 2(2-Oxo-1,3,2-dioxaphospholan-2-yloxy)ethyl methacrylate (3)

In a flask fitted with a magnetic stirrer, low temperature thermometer,and a pressure equalising funnel fitted with a silica gel guard tube,was placed a solution of 2-hydroxyethylmethacrylate (20. 00 g, 0. 154mol) and triethylamine (15.60 g; 0.154 mol) in dry diethyl ether (300ml). The solution was stirred and cooled to between -20° C. and -30° C.A solution of freshly distilled 2-chloro-2-oxo-1,3,2-dioxaphospholane(2)(21.9 g; 0.154 mol) in dry diethyl ether (20 ml) was then added dropwiseover 30 minutes, the temperature being held at -20° C. during theaddition. Stirring was continued at this temperature for a further 1hour and then for a further hour as the reaction mixture was allowed towarm to room temperature. The precipitated triethylamine hydrochloridewas removed by filtration, and was washed well with dry ether. The etherwas removed from the combined filtrate and washings by rotaryevaporation. The cloudy oil residue was then shaken for 5 minutes withdry diethyl ether (50 ml) to precipitate a further crop of triethylaminehydrochloride, which was again removed by filtration. Removal of theether on the rotary evaporator gave (3) (34.18 g; 94.3%) as a colourlessviscous oil.

IR (cm⁻¹, thin film) 1720, 1640, 1450, 1360, 1310, 1290, 1170, 1030,930, 850.

NMR (CDCl₃ ; 60MHz, 6 ppm) 1.95 (s,3H), 4.25-4.70 (m,8H), 5.70 (m,1H),6.25 (m,1H).

Rf 0.9 (SiO₂, eluting with 10% methanol:90% dichloromethane; spotvisualised with molybdenum blue spray reagent and with iodine vapour).

(d) 2(Methacryloyloxyethyl)-2'(trimethylammonium)ethyl phosphate innersalt (4).

The phospholane (3) (67.20 g; 0.285 mol) was dissolved in 100 ml of dryacetonitrile, and placed in a heavy walled tissue culture bottle. Thephospholane solution was then treated with a solution of anhydroustrimethylamine (25.74 g; 0.436 mol) in dry acetonitrile (100 ml). Thevessel was then sealed, and placed in a water bath held at 50° C. for 30hours. The vessel was opened, and the solution brought to the boil. Thesolution was filtered whilst hot, and then set aside forcrystallisation.

The product was collected by filtration, and most of the solvent removedby suction. The wet product was then washed thoroughly with anhydrousether, then dried under reduced pressure, to give (4) as a whiteamorphous, hygroscopic solid (51.16 g; 61%). Evaporation of the motherliquor gave a very viscous oil (20.00 g; 23%), from which furtherproduct (4) crystallised on standing at -20° C. TLC (silica gel plates,eluting with methanol/dichloromethane (1:1 v/v)) showed one spot Rf 0.1,which was revealed with Dragendorff's reagent, Molybdenum blue sprayreagent, and iodine vapour.

IR(cm⁻¹ 1720, 1640, 1320, 1300, 1230, 1170, 970, 750. NMR (D₂ O; 60MHz;δ ppm) 2.0 (s,3H), 3.27 (s,9H) 3.60-4.50 (m, 8H), 5.80, (m,lH) and 6.25(m,1H). CHN Found: C 42.98%, H 7.88%, N 4.42%, P 10.51%. CHN Theory: C44.75%, H 7.46%, N 4.75%, P 10.51%.

Reference Example 2: Synthesis ofdimethyl(2-methacroyloxyethyl)-(1(2-sulphopropyl)) ammonium betaineinner salt

2(Dimethylamino)ethylmethacrylate was vacuum distilled and thendissolved in 0.1 M dichloromethane. To this solution was added anequimolar amount of propane sultone. The betaine slowly precipitated outof solution and was recovered by filtration and washed with colddichloromethane. The reaction is shown in Reaction Scheme B.

Reference Example 3 Preparation of 14(4'-vinylbenzyloxy)butane!-2"-(trimethylammonium)ethyl phosphate innersalt.

The synthesis is depicted in Reaction Scheme C.

4-Hydroxy-1(4'-vinylbenzyloxy)butane (5)

Butanediol (40 ml; 40.68 g; 0.452 mol) was stirred in a 100 ml roundbottomed flask, and treated portionwise with potassium butoxide (17.60g; 0.144 mol). The initial reaction was exothermic. The reaction mixturewas stirred for 1.5 hours at room temperature. The resulting cloudysolution was then treated with chloromethyl styrene (20.00 g; 0.131mol). The styrene formed an upper, pale green layer, (the colourationbeing due to the presence of inhibitor), whose color darkenedconsiderably on the addition of 18-crown-6 (0.49 g; 1.86×10⁻³ mole). Theflask was stoppered, protected from light, and stirred for 28 hours atroom temperature. The mixture was then poured into water (120 ml) andextracted with dichloromethane (4×50 ml). The combined organic extractswere dried (MgSO₄) and evaporated to give viscous yellow oil (932.7 g).This oil was distilled from a small amount of CuCl to give a productshowing some impurities on TLC. The oil was then chromatographed onsilica gel, initially eluting with dichloromethane/petrol (1:1) toremove the impurities. The product was then eluted off the column withethyl acetate/petrol (1:1). Evaporation of the solvent gave a colourlessoil, which was distilled to give the desired styrylbutyl alcohol as acolourless oil b.pt. 150°-152°/0.4mbar. Yield 18.70 g; 69.2%.

NMR (60MHz: CDCl₃) 1.55 (m4H C--CH₂ --C) ; 3.50 (m, SH, 1H exch.; O--CH₂--, O--H), 4.45 (s,2H; Ar--CH₂ --), 5.50 (dd, 2H, vinylic), 6.75 (dd,vinylic), 7.40 (m, 4H, Ar--H).

IR 3402, 2938, 2888, 1631, 1602, 1582, 1511, 1480, 1445, 1382, 1320,1116, 1063, 920, 907, 827, 801, 716 and 667 cm⁻¹

4(2-Oxo-1.2.3-dioxaphospholane-2-yloxvl-1(4'- vinylbenzyloxy)butane (6)

4-Hydroxy-1(4'-vinylbenzyloxy)butane (5) (10.03 g; 48.69 mmol) and driedtriethylamine (4.92 g, 48.69 mmol) were dissolved in dry diethyl ether(150 ml) and the resulting solution placed in a rigorously dried flask.The solution was cooled to -30° C. and2-chloro-2-oxo-1,3,2-dioxaphospholane (6.94 g; 48.69 mmol) addeddropwise over 30 minutes, the temperature being held at -30° C. Thereaction mixture was then stirred for a further 2 hours, during whichtime the temperature was allowed to rise to 10° C. The mixture wasfiltered and the precipitate washed with dry ether. The filtrate wasevaporated (20° C./21mm) to give a cloudy oil. The residue was shakenwith 50 ml of dry ether and refiltered. Evaporation of the filtrate gavethe product as a viscous yellow oil (13.73 g; 90.4%).

TLC (eluting with 10% methanol 90% dichloromethane) showed one majorspot, which stained with acid molybdate reagent (Rf 0.61), IR (thinfilm) 3458, 2945, 2917, 2860, 1630, 1602, 1581, 1475, 1419, 1363, 1283,1103, 1032, 820, 842, 807, 800, 715, 610 and 421 cm⁻¹.

1 4(4'-Vinylbenzyloxy)butane!-2"(trimethylammonium)ethyl phosphate innersalt (7)

Trimethylamine (2.00 g, 33.9 mmol) was distilled into a reaction vessel,and frozen with liquid nitrogen. A solution of the4(2-oxo-1,3,2-dioxaphospholane-2-yloxy)-1-(4'-vinylbenzyloxy)butane (6)(10.00 g, 32.1 mmol) in anhydrous acetonitrile (40 ml) was then added tothe reaction vessel, which was then sealed and placed in a thermostattedwater bath (50° C. for 50 hours). The reaction vessel was then cooled toroom temperature, opened, and the reaction mixture evaporated to abouthalf its original volume (21 mm pressure). The concentrated solution wasthen stirred at room temperature, whilst anhydrous ether (200 ml) wasadded dropwise to precipitate the product as a viscous oil. The mixturewas then left for several hours at -10° C. The product was collected bydecanting off the supernatent solid. TLC (eluting withmethanol/dichloromethane 1:1) showed one major spot at Rf 0.0-0.1 whichstained with both Dragendorffs reagent and acid molybdate.

Reference Example 4 Preparation of2(acryloyloxyethyl)-2'-(trimethylammonium)ethyl phosphate inner salt

The synthesis is essentially analogous to that described in ReferenceExample 1 and uses a synthetic strategy analogous to that shown inReaction Scheme A.

(a) 2-(2-Oxo-1,3,2-dioxaphospholan-2-yloxy)ethyl acrylate

2-Hydroxyethyl acrylate (11.5 ml, 0.1 M) and triethylamine (14.6 ml) indry diethyl ether (250 ml) were cooled to -25° C. under nitrogen as asolution of 2-chloro-2-oxo-1,3,2-dioxaphospholane (14.3 g) in drydiethyl ether was added over 20 minutes. The mixture was stirred for afurther 1 hour at -20° C. and then allowed to warm to 10° C. over afurther hour. The precipitate was filtered, washed with ethyl acetate(100 ml) and the combined filtrate and washings evaporated under reducedpressue to give a pale yellow oil (21 g).

¹ H NMR (200MHz) d (CD₃ CN) 6.4 (1H,dd), 6.2 (1H,dd), 5.9 (1H,dd),4.0-3.6 (8H,complex) ppm.

(b) 2-(Acryloyloxyethyl)-2'-(trimethylammonium)ethyl phoshate, innersalt.

2-(2-Oxo1,3,2-dioxaphospholan-2yloxy) ethyl acrylate (21 g,0.095M) inacetonitile (50 ml) was treated with a solution of triethylamine (12.1g) in acetonitrile (150 ml) in a pressure reactor at 50° C. for 17hours. The mixture was cooled and some of the excess triethylamineremoved by evaporation under reduced pressure.

The solid material was filtered under nitrogen, washed with acetonitrile(20 ml) and diethylether (50 ml) and then dried under reduced pressue togive a colourless oil (12.1 g, 45%).

¹ H NMR (200MHz) d (D₂ O) 6.45 (1H,dd,J1.2 and 17.1 Hz), 6.25(1H,dd,J1.2 and 10.25Hz), 6.02 (1H,dd, J1.23 and 10.25Hz), 4.4 (2H,m),4.3 (2H, m), 4.2 (2H,m) 3.6(2H,m) and 3.2(9H,s) ppm.

Reference Example 5 Dodec-7-yn-1-ol Methacrylate

To dodec-7-yn-1-ol (25 g) in dichloromethane (60 ml) was added distilledtriethylamine (14.1 g). The mixture was cooled in an ice bath (0.5° C.)and stirred as distilled methacryloyl chloride (16.2 g) indichloromethane (50 ml) was added over 10 minutes. The temperature ofthe reation was allowed to warm to ambient and the mixture stirred fortwo hours. Water (150 ml) was added and the organic layer was removedand successively extracted with water (2×150 ml) and saturated sodiumbicarbonate solution (2×150 ml), washed with brine (150 ml) and driedover anhydrous sodium sulphate. The solvent was removed under reducedpressure to give a pale yellow oily liquid which was distilled underreduced pressure (0.18 mBar, 106°-110° C.) in the presence of copper (1)chloride to give dodec-7-yn-1-ol methacrylate, 17 g, 50% yield.

¹ H-NMR (200 MHz,d,ppm,CDCl₃): 0.90 (t,3H), 1.45 (m,10H), 1.70 (m,2H),1.95 (s,3H), 2.15 (m,6H), 4.15 (t,2H), 5.55 (s,1H), 6.10 (s,1H).##STR20## Steps (a) to (d) correspond with the steps in ReferenceExample 1 ##STR21##

We claim:
 1. A biocompatible polymer formed from monomers consisting of:(A) a radical polymerizable zwitterionic monomer containing azwitterionic group, (B) a radical polymerizable ionic comonomercontaining an ionic group, and, optionally, (C) a radicallypolymerisable diluent monomer, wherein the monomer A is a compound offormula Y--B--X,wherein X is a zwitterionic group; B is a straight orbranched alkylene, oxaalkylene, oligooxaalkylene chain optionallycontaining one or more fluorine atoms up to and including perfluorinatedchains, or if X contains a carbon-carbon chain between B and thezwitterion or if Y contains a terminal carbon atom bonded to B, avalence bond; Y is an ethylenically unsaturated polymerizable groupselected from ##STR22## wherein: R is hydrogen or a C₁₋₄ alkyl group; Ais --O-- or --NR¹ -- where R¹ is hydrogen or a C₁₋₄ alkyl group or R¹ is--B--X where B and X are as defined above; and K is selected from thegroup consisting of --(CH₂)_(p) OC(O)--, --(CH₂)_(p) C(O)O--,--(CH₂)_(p) OC(O)O--, --(CH₂)_(p) NR2--, --(CH₂)_(p) NR² C(O)--,(CH₂)_(p) C(O)NR² --, --(CH₂)_(p) NR² C(O)O--, --(CH₂)pOC (O) NR² --,--(CH₂)_(p) NR² C(O)NR² -- (in which R² may be the same or different),--(CH₂)_(p) O--, --(CH₂)_(p) SO₃ --, and, optionally in combination withB, a valence bond and p is from 1 to 12 and R² is hydrogen or a C₁₋₄alkyl group; wherein the comonomer (B) is a compound of formula Y² --B⁹--Q⁵ ; where Y² is an ethylenically unsaturated polymerizable groupselected from ##STR23## where R²⁶ is hydrogen or C₁₋₄ alkyl; A" is--O--or NR²⁷ --, wherein R²⁷ is hydrogen or a C₁₋₄ alkyl group or R²⁷ is--B⁹ Q⁵, B⁹ is a valence bond, a straight or branched alkyleneoxaalkylene or oligo-oxaalkylene group; K³ is --(CH₂)_(x) OC(O)--,--(CH),C(O))--, (CH₂)_(x) OC(O)--, --(CH₂)_(x) NR²⁸ --, --(CH₂)_(x) NR²⁸C(O)--, --(CH₂)^(x) C(O)NR²⁸ --, --(CH₂)_(x) NR²⁸ C(O)O--, --(CH₂)_(x)NR²⁸ --, --(CH₂)_(x) NR²⁸ C(O)NR²⁸ -- (in which the R²⁸ groups are thesame or different), --(CH₂)_(x) O--, --(CH₂)_(x) SO₃ --, a valence bond,x is from 1 to 12 and R²⁸ is hydrogen or a C₁₋₄ alkyl group; and Q⁵ isan ionic group, and wherein the diluent monomer (C) is a monomer nothaving said zwitterionic group or said ionic group, and is selected fromthe group consisting of an alkyl(alk)acrylate; an alkyl (alk)acrylamide: a hydroxyalkyl (alk)acrylate: vinyl pyrrolidone: styrene; apolyhydroxyl (alk)acrylate and a polyhydroxyl (alk)acrylamide in whichthe alkyl group contains from 1 to 4 carbon atoms; a polymerisable C₂₋₄alkene; a polymerisable butadiene; and a polymerisable acrylonitrile. 2.A polymer according to claim 1 formed from a monomer containing bothsaid zwitterionic group and said pendant ionic group.
 3. A polymeraccording to claim 1 in which the group Q⁵ is selected from the groupconsisting of carboxylate; sulphonate; hydrogen phosphate; phosphate;groups --NR³¹ ₃ ⁺ in which each group R³¹ is the same or different, andis hydrogen or alkyl of 1 to 6 carbon atoms two of which groups R³¹ maytogether form a heterocyclic ring containing from 5 to 7 atoms, groupsN⁺ Het, where Het is an unsaturated heterocyclic group substituted orunsubstituted by one or more alkyl groups of 1 to 4 carbon atoms; andgroups --PR³² ₃ ⁺ in which each group R³² is the same or different andis hydrogen or alkyl of 1 to 6 carbon atoms, two of which groups R³¹ maytogether form a heterocyclic ring containing 5 to 7 atoms.
 4. A polymeraccording to claim 3 in which the group Q⁵ is selected from the groupconsisting of carboxylate, sulphonate, phosphate and groups --NR³¹ ₃ ⁺in which each group R³¹ is the same or different and is hydrogen ormethyl.
 5. A polymer according to claim 1 in which X is selected fromgroups IVB, IVC, IVD, and IVF in which IVB has the formula ##STR24##wherein the groups R⁶ are the same or different and each is hydrogen orC₁₋₄ alkyl and d is from 2 to 4;group IVC has the formula ##STR25##wherein the groups R⁷ are the same or different and each is hydrogen orC₁₋₄ alkyl, and e is from 1 to 4; group IVD has the formula ##STR26##wherein the groups R⁸ are the same or different and each is hydrogen orC₁₋₄ alkyl, R^(8a) is hydrogen or a group --C(O)B¹ R^(8b) wherein R^(8b)is hydrogen or methyl, B¹ is a valence bond or straight or branchedalkylene, oxaalkylene or oligo-oxaalkyene group, and f is from 1 to 4;and if B is other than a valence bond z is 1 and if B is a valence bondz is 0, if X is directly bonded to an oxygen or nitrogen atom andotherwise z is 1; group IVE has the formula ##STR27## wherein the groupsR⁹ are the same or different and each is hydrogen or C₁₋₄ alkyl, R^(9a)is hydrogen or a group --C(O)B² R^(9b), wherein R^(9b) is hydrogen ormethyl, B² is a valence bond or a straight or branched alkylene,oxaalkylene or oligo-oxaalkylene group, and g is from 1 to 4; and if Bis other than a valence bond is 1 and if B is a valence bond z is 0 if Xis directly bonded to an oxygen or nitrogen atom and otherwise z is 1;and group IVF has the formula ##STR28## wherein the groups R¹⁰ are thesame or different and each is hydrogen or C₁₋₄ alkyl, R^(10a) ishydrogen or a group --C(O)B³ R^(10b) wherein R^(10b) is hydrogen ormethyl, B³ is a valence bond or a straight or branched alkylene,oxaalkylene or oligo-oxaalkylene group, and h is from 1 to 4; if B isother than a valence bond z is 1 and if B is a valence bond z is 0 if Xis directly bonded to the oxygen or nitrogen and otherwise z is
 1. 6. Apolymer according to claim 1 in which the ratio of zwitterionic monomerto ionic comonomer is in the range 5:95 to 95:5.
 7. A polymer accordingto claim 1 formed from monomers including 5 to 50% by mole of diluentmonomer not having said zwitterionic group or said ionic group.
 8. Apolymer-forming process comprising the step of forming a biocompatiblepolymer by radical polymerization of (A) a zwitterionic monomercontaining a zwitterionic group and (B) a comonomer containing an ionicgroup,wherein the monomer A is a compound of formula Y--B--X. wherein Bis a straight or branched alkylene, oxaalkylene, oligooxaalkylene chainoptionally containing one or more fluorine atoms up to and includingperfluorinated chains, or if X contains a carbon-carbon chain between Band the center of permanent position charge or if Y contains a terminalcarbon atom bonded to B, a valence bond; X is a zwitterionic group, andY is an ethylenically unsaturated polymerizable group selected from##STR29## wherein: R is hydrogen or a C₁₋₄ alkyl group; A is --O-- or--NR¹ -- where R¹ is hydrogen or a C₁₋₄ alkyl group or R¹ is --B--Xwhere B and X are as defined above; and K is selected from the groupconsisting of --(CH₂)_(p) OC(O)--, --(CH₂)_(p) C(O)O--, --(CH₂)_(p)OC(O)O--, (CH₂)_(p) NR² --, --(CH₂)_(p) NR² C(O)--, (CH₂)_(p) C(O)NR²--, --(CH₂)_(p) NR² C(O)O--, --(CH₂)OC(O)NR² --, --(CH₂)_(p) NR² C(O)NR²-- (in which R² may be the same or different), --(CH₂)_(p) O--,--(CH₂)_(p) SO₃ --, and, optionally in combination with B, a valencebond and p is from 1 to 12 and R² is hydrogen or a C₁₋₄ alkyl group; andwherein the comonomer B is a compound of formula Y² --B⁹ --Q⁵ ; where Y²is an ethylenically unsaturated polymerizable group selected from##STR30## where R²⁶ is hydrogen or C₁₋₄ alkyl; A" is --O-- or NR²⁷ --,wherein R²⁷ is hydrogen or a C₁₋₄ alkyl group or R²⁷ is --B⁹ Q⁵, B⁹ is avalence bond, a straight or branched alkylene oxaalkylene oroligo-oxaalkylene group; K³ is --(CH₂)_(x) OC(O)--, --(CH)_(x) C(O))--,(CH₂)_(x) OC(O)--, --(CH₂)_(x) NR²⁸ --, --(CH₂)_(x) NR²⁸ C(O)--,--(CH₂)_(x) C(O)NR²⁸ --, --(CH₂)_(x) NR²⁸ C(O)O--, --(CH₂)_(x) OC(O)NR²⁸--, --(CH₂)_(x) NR²⁸ C(O)NR²⁸ -- (in which the R²⁸ groups are the sameor different), --(CH₂)_(x) O--, --(CH₂)_(x) SO₃ --, a valence bond, x isfrom 1 to 12 and R²⁸ is hydrogen or a C₁₋₄ alkyl group; and Q⁵ is anionic group.
 9. A polymer according to claim 4 in which X is selectedfrom groups IVB, IVC, IVD, IVE, and IVF, in which IVB has the formula##STR31## wherein the groups R⁶ are the same or different and each ishydrogen or C₁₋₄ alkyl and d is from 2 to 4;group IVC has the formula##STR32## wherein the groups R⁷ are the same or different and each ishydrogen or C₁₋₄ alkyl, and e is from 1 to 4; group IVD has the formula##STR33## wherein the groups R⁸ are the same or different and each ishydrogen or C₁₋₄ alkyl, R^(8a) is hydrogen or a group --C(O)B¹ R^(8b)wherein R^(8b) is hydrogen or methyl, B¹ is a valence bond or straightor branched alkylene, oxaalkylene or oligo-oxaalkyene group, and f isfrom 1 to 4; and if B is other than a valence bond z is 1 and if B is avalence bond z is 0, if X is directly bonded to an oxygen or nitrogenatom and otherwise z is 1; group IVE has the formula ##STR34## whereinthe groups R⁹ are the same or different and each is hydrogen or C₁₋₄alkyl, R^(9a) is hydrogen or a group --C(O)B² R^(9b), wherein R^(9b) ishydrogen or methyl, B² is a valence bond or a straight or branchedalkylene, oxaalkylene or oligo-oxaalkylene group, and g is from 1 to 4;and if B is other than a valence bond is 1 and if B is a valence bond zis 0 if X is directly bonded to an oxygen or nitrogen atom and otherwisez is 1; and group IVF has the formula ##STR35## wherein the groups R¹⁰are the same or different and each is hydrogen or C₁₋₄ alkyl, R^(10a) ishydrogen or a group --C(O)B³ R^(10b) wherein R^(10b) is hydrogen ormethyl, B³ is a valence bond or a straight or branched alkylene,oxaalkylene or oligo-oxaalkylene group, and h is from 1 to 4; if B isother than a valence bond z is 1 and if B is a valence bond z is 0 if Xis directly bonded to the oxygen or nitrogen and otherwise z is
 1. 10. Apolymer according to claim 1 in which the comonomer containing an ionicgroup is a compound of formula CH₂ ═C (R²⁶)--C (O)--A"--B⁹ --Q⁵,whereR²⁶ is hydrogen or methyl; A" is --O--; B⁹ is an alkylene group offormula --(CH₂)_(y) --, in which y is 1 to 12 or B⁹ is a bond; and Q⁵ isan ionic group selected from a carboxylate group, a sulphonate group, ahydrogen phosphonate group, a phosphate group, a hydroxyl group andgroups +NR²¹ ₃ in which each group R³¹ is the same or different and ishydrogen or methyl, provided that Q⁵ can be hydroxyl only when B⁹ is abond.
 11. A polymer according to claim 1 in which the monomer containinga zwitterionic group is a compound of formula CH₂ ═C(R)--C(O)--A--B--Xwherein R is hydrogen or methyl;A is --O--; B is an alkylene group offormula --(CH₂)_(a) --, wherein a is from 1 to 12; and X is a group offormula IVC ##STR36## wherein the groups R⁷ are the same or differentand each is hydrogen or C₁₋₄ -alkyl; and e is from 1 to
 4. 12. A polymeraccording to claim 10 in which the monomer containing a zwitterionicgroup is a compound of the general formula CH₂ ═C(R)--C(O)--A--B--Xwherein R is hydrogen or methyl;A is --O--; B is an alkylene group offormula --(CH₂)_(a) --, wherein a is from 1 to 12; and X is a group offormula IVC ##STR37## wherein the groups R⁷ are the same or differentand each is hydrogen or C₁₋₄ -alkyl; and e is from 1 to 4.